This work was supported from China Postdoctoral Science Foundation (Grant No. 2017M612348), Qingdao Postdoctoral Foundation (Grant No. 3002000-861805033070) and from the Young Talent Project at Ocean University of China (Grant No. 3002000-861701013151). The authors thank Miss Ya Chong Li for preparing the narration.

1. Optimize the atomic structure.
<ol>
	<li>Prepare four input files for structure relaxation calculation by VASP: INCAR, POSCAR, POTCAR, and KPOINTS. 
	NOTE: There are specified parameters in the INCAR file that define the calculation. The line &#34;EDIFFG = 0.02&#34; in the INCAR file indicates that all atoms are relaxed until the force on each atom is &#60;0.02 eV/&#197;. The POSCAR file contains the atomic geometry information. The initial lattice parameters in the POSCAR file can be chosen from theoretical3 or experimental references12,13. The KPOINTS file defines the k point mesh and POTCAR is the pseudopotential file. The order of atom types in POSCAR should be the same as that in POTCAR. Examples of input files for structure relaxation are shown in the Supplementary Materials (except the pseudopotential file, which needs a license from VASP).
	<ol>
		<li>Generate the initial structure of boron nitride (BN) nanoribbons (NR) for &#34;POSCAR&#34;.
		<ol>
			<li>Download the POSCAR file for the BN bulk unit from https://materialsproject.org.</li>
			<li>Use v2xsf to convert the POSCAR file to a file in xsf format that can be read by xcrysden. Type v2xsf POSCAR on the terminal in the Ubuntu system to get &#34;POSCAR.xsf.gz&#34;. Type gunzip POSCAR.xsf.gz and output the POSCAR.xsf file.</li>
			<li>Use xcrysden to build the BN supercell.
			<ol>
				<li>Type xcrysden --xsf POSCAR.xsf on the terminal in the Ubuntu system. Select the menu Modify/Number of Units Drawn and extend the cell in the X and Y directions.</li>
				<li>Select the menu File/Save XSF Structure to export the supercell structure, named &#34;supercell&#34;. 
				NOTE: The name of the structure is an arbitrary definition.</li>
			</ol>
			</li>
			<li>Use xmakemol to open the supercell. Type xmakemol -f supercell on the terminal in the Ubuntu system. Select the menu Edit/Visible. Click Toggle to delete the atoms inside the region and cut the NR to the desired width and chirality.</li>
		</ol>
		</li>
		<li>Generate the initial structure of the BN nanotube (NT) for POSCAR. Download &#34;NanotubeModeler&#34; from http://www.jcrystal.com/products. Open NanotubeModeler.exe in the Windows system. Select the menu Select type/B-N and specify the chirality. Select the menu File/Save XYZ table to export the structure.</li>
		<li>Generate the initial structure of the nanocomposite by encapsulating the NR (from step 1.1.1) inside the NT (from step 1.1.2). 
		NOTE: The encapsulation can be finished by adjusting the Cartesian coordinates of the NR and the NT10,14,15.</li>
		<li>Use the vmd software to check the atomic structure before submitting the calculation job.
		<ol>
			<li>Type vmd on the terminal in the Ubuntu system. In the opened vmd main window, select the menu File/New Molecule and find the POSCAR file through the Browse window. Load POSCAR by typing VASP_POSCAR.</li>
			<li>Display the structure in different styles in the Graphical Representations/Drawing Method window. 
			NOTE: For example, once the CPK is chosen, each atom (bond) is represented by a sphere (stick). The installation guide and full tutorial of vmd are available at http://www.ks.uiuc.edu/Research/vmd.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Type qsub job.pbs on the terminal in the Linux system to submit the job to the computer cluster. 
	NOTE: &#34;job.pbs&#34; represents the name of the PBS script. The name of the PBS script is an arbitrary definition. The four input files together with the PBS script should be at the working directory. The command qsub job.pbs will be used in steps 2.2, 3.2, 3.5.2, and section 4. An example of a PBS script can be found in the supplementary coding file. After the submitted job is finished, if &#34;reached required accuracy - stopping structural energy minimization&#34; appears at the end of the output log, the converged result is obtained. The resulting CONTCAR file will be used as the input file POSCAR in steps 2.1, 3.1, 3.5.1, 3.5.3.1, 4.1.1, 4.1.4, and section 4.2.</li>
</ol>
2. Calculate the encapsulation energy.
<ol>
	<li>Type mkdir nanocomposite isolated-nanoribbon isolated-nanotube to create three folders for the nanocomposite, the NR, and the NT on a terminal in a Linux system. Prepare one PBS script &#34;job.pbs&#34; and four input files INCAR, POSCAR, POTCAR, and KPOINTS for the energy calculation in each folder. 
	NOTE: The input file POSCAR is the file named CONTCAR with the relaxed structure from step 1. Examples of input files are given in Supplementary Materials (except POTCAR).</li>
	<li>Go to each folder and type qsub job.pbs on the terminal in the Linux system. 
	NOTE: The three submitted jobs will perform the static self-consistent energy calculations for the nanocomposite, isolated NR, and isolated NT, respectively.</li>
	<li>Extract the total energy from the file OUTCAR for each system after finishing the static self-consistent calculations. Type grep &#8220;free energy TOTEN&#8221; ./nanocomposite/OUTCAR | tail -n 1, grep &#8220;free energy TOTEN&#8221; ./isolated-nanoribbon/OUTCAR | tail -n 1, and grep &#8220;free energy TOTEN&#8221; ./isolated-nanotube/OUTCAR | tail -n 1. Define the three displayed values as ENT+NR, ENR, and ENT, respectively. Calculate the encapsulation energy per angstrom: EL = (ENT+NR - ENT -ENR)/L14,15. 
	NOTE: The periodical direction in each system is along the Z axis and L is the lattice constant of the unit cell along the Z axis. Test calculations of the energy dependence on the plane wave cutoff energy and the k point mesh are needed. The encapsulation energy can be used as an estimate for the energetic stability of the nanocomposite.</li>
</ol>
3. Extract the electronic properties from the band structure.
<ol>
	<li>Prepare one PBS script &#34;job.pbs&#34; and six input files: INCAR, POSCAR, POTCAR, KPOINTS, CHGCAR, and CHG for band calculation. Set ICHARG = 11 in INCAR. 
	NOTE: The preconverged CHGCAR and CHG files are from the static self-consistent calculations in step 2.2. The band analysis is at the PBE level. The k point sampling in the KPOINTS file is in line-mode. Examples of input files for this step can be found in the Supplementary Materials (except POTCAR).</li>
	<li>Type qsub job.pbs on the terminal in the Linux system to submit the job.</li>
	<li>Use P4VASP to generate the projected band.
	<ol>
		<li>Load &#34;vasprun.xml&#34; by typing p4v vasprun.xml on terminal in the Ubuntu system. 
		NOTE: &#34;p4v&#34; is used to start P4VASP. The file &#34;vasprun.xml&#34; should be at the working directory.</li>
		<li>Select the menu Electronic/Local DOS+bands control and then Select/Bands.
		<ol>
			<li>Specify the atomic numbers of NT in the section Atom selection. Get the atomic number by pointing to the corresponding atoms using vmd as mentioned in step 1.1.4. Specify the color, type, and size of the symbol for the projected band structure through the menu Symbol and Symbol size. Press the menu Add new line. 
			NOTE: The graph will show the band structure with contributions from the NT.</li>
			<li>Repeat the same procedure following step 3.3.2.1 to get the projected band with contributions from the NR.</li>
		</ol>
		</li>
		<li>Select the menu Graph/Export. Export the graph into a file with an agr format (for example, as &#34;11-4.agr&#34;). 
		NOTE: The output data of the projected bands by P4VASP are in three columns where the third one represents the weighting.</li>
	</ol>
	</li>
	<li>Use xmgrace to edit the projected band.
	<ol>
		<li>Type xmgrace 11-4.agr on the terminal to start xmgrace in the Ubuntu system. Select the menu Plot/Axis properties to edit the label and range of the axis.</li>
		<li>Select the menu Plot/Set appearance to read the energy value at the specified band number and k point. 
		NOTE: The valence band maximum (VBM) and conduction band minimum (CBM) of NR/NT can be read from the projected band with contributions on NR/NT, respectively. According to the band alignments, heterostructures can be classified into three types: type I (VBMNT &#60;VBMNR &#60;CBMNR &#60;CBMNT or VBMNR &#60;VBMNT &#60;CBMNT &#60;CBMNR), type II (VBMNT &#60;VBMNR &#60;CBMNT &#60;CBMNR or VBMNR &#60;VBMNT &#60;CBMNR &#60;CBMNT), or type III (VBMNT &#60;VBMNT &#60;CBMNR &#60;CBMNR or VBMNR &#60;VBMNR &#60;CBMNT &#60;CBMNT)9.</li>
		<li>Calculate the valence band offset (VBO), conduction band offset (CBO), and the band gap following Kang et al.16.</li>
		<li>Select the menu File/Print to export the graph with eps format.</li>
	</ol>
	</li>
	<li>Calculate the band decomposed charge density for the VBM and CBM.
	<ol>
		<li>Prepare one PBS script &#34;job.pbs&#34; and seven input files: INCAR, POSCAR, POTCAR, KPOINTS, WAVECAR, CHGCAR, and CHG. Specify the band numbers for the CBM and VBM by the tag IBAND in INCAR. Use the single corresponding k point for each band edge. 
		NOTE: The preconverged CHGCAR, CHG, and WAVECAR files are from the static self-consistent calculations in step 2.2. Examples of input files for this step are given in the Supplementary Materials (except POTCAR).</li>
		<li>Type qsub job.pbs on the terminal in the Linux system to submit the job.</li>
		<li>Use vmd to plot the VBM and CBM in real space after the job is finished.
		<ol>
			<li>Start a vmd session and load the POSCAR file as in step 1.1.4.</li>
			<li>Select the menu File/New Molecule in the vmd main window. Find the PARCHG file through the Browse window. Load PARCHG by typing VASP_PARCHG.</li>
			<li>Select the menus Draw/Solid Surface and Show/Isosurface in the Graphical Representations window. Change the isovalue to an appropriate value (for example, 0.02). Change the color of the isosurface through the menu Coloring Method. 
			NOTE: This is an intuitive analysis for band types with respect to that in step 3.4. Generally, the atomic structure is arranged away from the boundary, otherwise the visualized charge density is not shown in a continuous manner. Please see Supplemental Figure 1 for details.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
4. Modulate the electronic properties of the nanocomposite (NT encapsulated inside NR) by external fields.
<ol>
	<li>Add a transverse electric field to the nanocomposite17.
	<ol>
		<li>Prepare one PBS script &#34;job.pbs&#34; and four input files: INCAR, POSCAR, POTCAR, and KPOINTS.</li>
		<li>Define the strength of the electric field by the tag &#34;EFIELD&#34; in units of eV/&#197;.</li>
		<li>Set LDIPOL = T. Specify IDIPOL with an exact value (1, 2, or 3). 
		NOTE: These two tags are added to include dipole corrections. The electric field will be applied along the X, Y, or Z axis by setting the value of IDIPOL to 1, 2, or 3.</li>
		<li>Perform the static self-consistent calculations and band structure calculations following sections 2 and 3 without structural optimization. 
		NOTE: Previous studies indicate that electric fields over 5 V/&#197; can be used to modify the band gap of BN-NT and BN-NR without deforming the structure18,19.</li>
	</ol>
	</li>
	<li>Add a longitudinal tensile strain to the nanocomposite.
	<ol>
		<li>Change the lattice parameters along the periodical direction to reflect the strain effect. 
		NOTE: For example, the optimized lattice parameter of the nanocomposite along the Z axis is 2.5045 &#197;. If 1% uniaxial tensile strain is applied along the Z direction, change the lattice parameter in POSCAR to 2.5045 x 1.01 = 2.529545 &#197;.</li>
		<li>Relax the modified structure following section 1.</li>
		<li>Perform static self-consistent calculations and band structure calculations following sections 2 and 3.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Collins, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accelerated+discovery+of+two+crystal+structure+types+in+a+complex+inorganic+phase+field.">Accelerated discovery of two crystal structure types in a complex inorganic phase field.</a> Nature. 546 (7657), 280-284 (2017).</li><li>Jain, A., Shin, Y., Persson, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computational+predictions+of+energy+materials+using+density+functional+theory.">Computational predictions of energy materials using density functional theory.</a> Nature Reviews Materials. 1 (1), 15004 (2016).</li><li>de Jong, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Charting+the+complete+elastic+properties+of+inorganic+crystalline+compounds.">Charting the complete elastic properties of inorganic crystalline compounds.</a> Scientific Data. 2, 150009 (2015).</li><li>Fu, C. F., Wu, X. J., Yang, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Material+Design+for+Photocatalytic+Water+Splitting+from+a+Theoretical+Perspective.">Material Design for Photocatalytic Water Splitting from a Theoretical Perspective.</a> Advanced Materials. 30 (48), 1802106 (2018).</li><li>Gu, T., Luo, W., Xiang, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prediction+of+two-dimensional+materials+by+the+global+optimization+approach.">Prediction of two-dimensional materials by the global optimization approach.</a> Wiley Interdisciplinary Reviews-Computational Molecular Science. 7 (2), e1295 (2017).</li><li>Lejaeghere, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reproducibility+in+density+functional+theory+calculations+of+solids.">Reproducibility in density functional theory calculations of solids.</a> Science. 351 (6280), aad3000 (2016).</li><li>Kresse, G., Furthm&#252;ller, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+Iterative+Schemes+for+ab+Initio+Total-Energy+Calculations+Using+a+Plane-Wave+Basis+Set.">Efficient Iterative Schemes for ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set.</a> Physical Review B. 54 (16), 11169-11186 (1996).</li><li>Perdew, J. P., Burke, K., Ernzerhof, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generalized+Gradient+Approximation+Made+Simple.">Generalized Gradient Approximation Made Simple.</a> Physical Review Letters. 77 (18), 3865-3868 (1996).</li><li>Ozcelik, V. O., Azadani, J. G., Yang, C., Koester, S. J., Low, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Band+alignment+of+two-dimensional+semiconductors+for+designing+heterostructures+with+momentum+space+matching.">Band alignment of two-dimensional semiconductors for designing heterostructures with momentum space matching.</a> Physical Review B. 94 (3), 035125 (2016).</li><li>Gong, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robust+staggered+band+alignment+in+one-dimensional+van+der+Waals+heterostructures:+binary+compound+nanoribbons+in+nanotubes.">Robust staggered band alignment in one-dimensional van der Waals heterostructures: binary compound nanoribbons in nanotubes.</a> Journal of Materials Chemistry C. 7 (13), 3829-3836 (2019).</li><li>Grimme, S., Antony, J., Ehrlich, S., Krieg, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Consistent+and+Accurate+ab+Initio+Parametrization+of+Density+Functional+Dispersion+Correction+(DFT-D)+for+the+94+Elements+H-Pu.">A Consistent and Accurate ab Initio Parametrization of Density Functional Dispersion Correction (DFT-D) for the 94 Elements H-Pu.</a> Journal of Chemical Physics. 132 (15), 154104 (2010).</li><li>Zhang, L., Chen, Z. Q., Su, J., Li, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Data+mining+new+energy+materials+from+structure+databases.">Data mining new energy materials from structure databases.</a> Renewable &amp; Sustainable Energy Reviews. 107, 554-567 (2019).</li><li>Zakutayev, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+open+experimental+database+for+exploring+inorganic+materials.">An open experimental database for exploring inorganic materials.</a> Scientific Data. 5, 180053 (2018).</li><li>Kou, L. Z., Tang, C., Frauenheim, T., Chen, C. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intrinsic+Charge+Separation+and+Tunable+Electronic+Band+Gap+of+Armchair+Graphene+Nanoribbons+Encapsulated+in+a+Double-Walled+Carbon+Nanotube.">Intrinsic Charge Separation and Tunable Electronic Band Gap of Armchair Graphene Nanoribbons Encapsulated in a Double-Walled Carbon Nanotube.</a> Journal of Physical Chemistry Letters. 4 (8), 1328-1333 (2013).</li><li>Kou, L. Z., Tang, C., Wehling, T., Frauenheim, T., Chen, C. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emergent+properties+and+trends+of+a+new+class+of+carbon+nanocomposites:+graphene+nanoribbons+encapsulated+in+a+carbon+nanotube.">Emergent properties and trends of a new class of carbon nanocomposites: graphene nanoribbons encapsulated in a carbon nanotube.</a> Nanoscale. 5 (8), 3306-3314 (2013).</li><li>Kang, J., Tongay, S., Zhou, J., Li, J. B., Wu, J. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Band+offsets+and+heterostructures+of+two-dimensional+semiconductors.">Band offsets and heterostructures of two-dimensional semiconductors.</a> Applied Physics Letters. 102 (1), 012111 (2013).</li><li>Makov, G., Payne, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Periodic+boundary+conditions+in+ab+initio+calculations.">Periodic boundary conditions in ab initio calculations.</a> Physical Review B. 51 (7), 4014-4022 (1995).</li><li>Chen, C., Lee, M., Clark, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Band+gap+modification+of+singlewalled+carbon+nanotube+and+boron+nitride+nanotube+under+a+transverse+electric+field.">Band gap modification of singlewalled carbon nanotube and boron nitride nanotube under a transverse electric field.</a> Nanotechnology. 15 (12), 1837 (2004).</li><li>Zhang, Z. H., Guo, W. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Energy-gap+Modulation+of+BN+Ribbons+by+Transverse+Electric+Fields:+First-Principles+Calculations.">Energy-gap Modulation of BN Ribbons by Transverse Electric Fields: First-Principles Calculations.</a> Physical Review B. 77 (7), 075403 (2008).</li><li>Sahin, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monolayer+Honeycomb+Structures+of+Group-IV+Elements+and+III-V+Binary+Compounds:+First-Principles+Calculations.">Monolayer Honeycomb Structures of Group-IV Elements and III-V Binary Compounds: First-Principles Calculations.</a> Physical Review B. 80 (15), 155453 (2009).</li><li>Yang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+Photocatalytic+Hydrogen+Generation+and+Capsule+Storage+in+Graphene+Based+Sandwich+Structures.">Combining Photocatalytic Hydrogen Generation and Capsule Storage in Graphene Based Sandwich Structures.</a> Nature Communications. 8, 16049 (2017).</li><li>Neugebauer, J., Scheffler, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adsorbate-substrate+and+adsorbate-adsorbate+interactions+of+Na+and+K+adlayers+on+Al(111).">Adsorbate-substrate and adsorbate-adsorbate interactions of Na and K adlayers on Al(111).</a> Physical Review B. 46 (24), 16067 (1992).</li><li>He, W., Li, Z. Y., Yang, J. L., Hou, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electronic+structures+of+organic+molecule+encapsulated+BN+nanotubes+under+transverse+electric+field.">Electronic structures of organic molecule encapsulated BN nanotubes under transverse electric field.</a> Journal of Chemical Physics. 124 (15), 154709 (2006).</li><li>Zhang, R. Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+Z-Scheme+Water+Splitting+Photocatalyst+Based+on+Two-Dimensional+Van+Der+Waals+Heterostructures.">Direct Z-Scheme Water Splitting Photocatalyst Based on Two-Dimensional Van Der Waals Heterostructures.</a> Journal of Physical Chemistry Letters. 9 (18), 5419-5424 (2018).</li><li>Paiera, J., Marsman, M., Hummer, K., Kresse, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Screened+hybrid+density+functionals+applied+to+solids.">Screened hybrid density functionals applied to solids.</a> Journal of Chemical Physics. 124 (15), 154709 (2006).</li><li>Pyzer-Knapp, E. O., Suh, C., G&#243;mez-Bombarelli, R., Aguilera-Iparraguirre, J., Aspuru-Guzik, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What+Is+High-Throughput+Virtual+Screening?+A+Perspective+from+Organic+Materials+Discovery.">What Is High-Throughput Virtual Screening? A Perspective from Organic Materials Discovery.</a> Annual Review of Materials Research. 45, 195-216 (2015).</li><li>Cerqueira, T. F. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+Novel+Cu,+Ag,+and+Au+Ternary+Oxides+from+Global+Structural+Prediction.">Identification of Novel Cu, Ag, and Au Ternary Oxides from Global Structural Prediction.</a> Chemistry of Materials. 27 (13), 4562-4573 (2015).</li></ol>

The authors have nothing to disclose.

The calculations for electronic properties in sections 2, 3, and 4 would be similar among various nanoscale materials. The initial atomic model in step 1 should be carefully designed to extract meaningful information. For example, the factor for selecting the model could be the size or chirality of the materials. Also, the initial atomic model in step 1.1 should be reasonably prepared for low-cost structure relaxation. Taking the nanocomposite in the protocol as an example, the NR should be encapsulated inside the NT in ...

The worldwide demand for clean and sustainable energy has spurred research for promising materials to reduce dependence on finite petroleum resources. Simulations are more efficient and economical than experiments in accelerating the search for new functional materials1. Material design from a theoretical perspective2,3,4 is now more and more popular due to rapid advances in computational resources and theory developments, making computational simulations more reliable5. The density functional theory (DFT) calculations implemented in many codes are becoming more robust and yield reproducible results6.
The Vienna Ab initio Simulation Package&#160;(VASP)7 presents one of the most promising DFT codes for predicting molecular and crystalline properties and more than 40,000 studies making use of this code have been published. Most work is performed at the Perdew-Burke-Ernzerhof (PBE) functional level8, which underestimates the band gap sizes, but captures the essential trends in band alignment and band offsets3. This protocol aims to outline the details of investigating the band edge profiles and bandgaps of nanoscale materials for clean and renewable energy using this computational tool. More examples using VASP are available at https://www.vasp.at.
This report presents the computational screening of one-dimensional (1D) vdW heterostructures with type II band alignments9 for a promising application in photocatalytic water splitting4. Specifically, nanoribbons (NRs) encapsulated inside nanotubes (NTs) are examined as an example10. To address noncovalent interactions, vdW corrections using the DFT-D3 method are included11. The DFT calculations in steps 1.2, 2.2, 3.2, 3.5.2, and section 4 by VASP are performed using a Portable Batch System (PBS) script by the high-performance research computers in the CenTOS system. An example of a PBS script is shown in the Supplementary Materials. The data postprocessing by the P4VASP software in step 3.3 and the figure plot by the xmgrace software in step 3.4 are carried on a local computer (laptop or desktop) in the Ubuntu system.

<table><tbody><tr><td>Nanotube Modeler</td><td>Developed by Dr. Steffen Weber</td><td>NanotubeModeler1.8</td><td>http://www.jcrystal.com/products/wincnt/NanotubeModeler.exe</td></tr><tr><td>P4VASP</td><td>Orest Dubay</td><td>p4vasp 0.3.30</td><td>Open source, available at www.p4vasp.at</td></tr><tr><td>v2xsf</td><td>Developed by Dr. Jens Kunstmann</td><td>v2xsf</td><td>http://theory.chm.tu-dresden.de/~jk/software.html</td></tr><tr><td>VASP software</td><td>Computational Materials Physics, Dept. of Physics, University of Vienna</td><td>vasp.5.4.1</td><td>https://www.vasp.at</td></tr><tr><td>VMD software</td><td>Theoretical and Computational Biophysics Group, University of Illinois at Urbana-Champaign</td><td>vmd1.9.3</td><td>https://www.ks.uiuc.edu/Research/vmd</td></tr><tr><td>xcrysden</td><td>Dept. of Physical and Organic Chemistry, Jozef Stefan Institute</td><td>XCrySDen1.5.60</td><td>http://www.xcrysden.org/</td></tr><tr><td>Xmakemol</td><td>Developed by M. P. Hodges</td><td>xmakemol5.16</td><td>https://www.nongnu.org/xmakemol/XmakemolDownloads.html</td></tr><tr><td>Xmgrace software</td><td>Grace Development Team under the coordination of Evgeny Stambulchik</td><td>xmgrace5.1.25</td><td>http://plasma-gate.weizmann.ac.il/Grace/</td></tr></tbody></table>

probe type ii band alignment in one-dimensional van der waals heterostructures using first-principles calculations

Computational tools based on density-functional theory (DFT) enable the exploration of the qualitatively new, experimentally attainable nanoscale compounds for a targeted application. Theoretical simulations provide a profound understanding of the intrinsic electronic properties of functional materials. The goal of this protocol is to search for photocatalyst candidates by computational dissection. Photocatalytic applications require suitable band gaps, appropriate band edge positions relative to the redox potentials. Hybrid functionals can provide accurate values of these properties but are computationally expensive, whereas the results at the Perdew-Burke-Ernzerhof (PBE) functional level could be effective for suggesting strategies for band structure engineering via electric field and tensile strain aiming to enhance the photocatalytic performance. To illustrate this, in the present manuscript, the DFT based simulation tool VASP is used to investigate the band alignment of nanocomposites in combinations of nanotubes and nanoribbons in the ground state. To address the lifetime of photogenerated holes and electrons in the excited state, nonadiabatic dynamics calculations are needed.

Zigzag BN-NRs encapsulated inside armchair BN-NTs (11,11) were chosen as representative examples for a 1D vdW heterostructure. The lattice parameters were taken from Sahin et al.20. For convenience, zigzag NRs are abbreviated Zn, where n represents the III&#8211;V dimers along the width14. The encapsulation energy EL from step 2.3 was used as a rough estimate for the energetic stability of the nanocomposite. The EL values of Z2, Z...

Watch this Scientific Journal Video about Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations at JoVE.com

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Calculations performed by the Vienna Ab initio Simulation Package can be used to identify the intrinsic electronic properties of nanoscale materials and predict the potential water-splitting photocatalysts.

Computational tools based on density-functional theory (DFT) enable the exploration of the qualitatively new, experimentally attainable nanoscale ...

probe-type-ii-band-alignment-one-dimensional-van-der-waals

Universidad de Cartagena UDEC

Research

JoVE Journal

Chemistry

7.5K Views.  Ocean University of China. Calculations performed by the Vienna Ab initio Simulation Package can be used to identify the intrinsic electronic properties of nanoscale materials and predict the potential water-splitting photocatalysts.

Video: Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

In recent years &pi;-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication.	
A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently &pi;-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important &pi;-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors and spintronics.	
Recently we have been able to address the above-mentioned issue by employing a novel "centrifugation-assisted" approach. This method therefore broadens the spectrum of organic materials that can be patterned in a vertically ordered nanowire array. Due to the technological importance of Alq3, rubrene and methanofullerenes, our method can be used to explore how the nanostructuring of these materials affects the performance of aforementioned organic devices. The purpose of this article is to describe the technical details of the above-mentioned protocol, demonstrate how this process can be extended to grow small-molecular organic nanowires on arbitrary substrates and finally, to discuss the critical steps, limitations, possible modifications, trouble-shooting and future applications.

We report a simple method for fabricating an ultrahigh density array of vertically ordered small-molecular organic nanowires. This method allows for synthesis of complex heterostructured hybrid nanowire geometries, which can be inexpensively grown on arbitrary substrates. These structures have potential applications in organic electronics, optoelectronics, chemical sensing, photovoltaics and spintronics.

In  recent years &pi;-conjugated  organic semiconductors have emerged as the active material in a number of  diverse applications including large-area, ...

Engineering

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM). ECCI allows for imaging of defects and crystallographic features under specific diffraction conditions, similar to that possible via plan-view transmission electron microscopy (PV-TEM). A particular advantage of the ECCI technique is that it requires little to no sample preparation, and indeed can use large area, as-produced samples, making it a considerably higher throughput characterization method than TEM. Similar to TEM, different diffraction conditions can be obtained with ECCI by tilting and rotating the sample in the SEM. This capability enables the selective imaging of specific defects, such as misfit dislocations at the GaP/Si interface, with high contrast levels, which are determined by the standard invisibility criteria. An example application of this technique is described wherein ECCI imaging is used to determine the critical thickness for dislocation nucleation for GaP-on-Si by imaging a range of samples with various GaP epilayer thicknesses. Examples of ECCI micrographs of additional defect types, including threading dislocations and a stacking fault, are provided as demonstration of its broad, TEM-like applicability. Ultimately, the combination of TEM-like capabilities &#8211; high spatial resolution and richness of microstructural data &#8211; with the convenience and speed of SEM, position ECCI as a powerful tool for the rapid characterization of crystalline materials.

The use of electron channeling contrast imaging in a scanning electron microscope to characterize defects in III-V/Si heteroexpitaxial thin films is described. This method yields similar results to plan-view transmission electron microscopy, but in significantly less time due to lack of required sample preparation.

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging ...

Atomically Traceable Nanostructure Fabrication

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.

We report a protocol for combining the atomic metrology of the Scanning Tunneling Microscope for surface patterning with selective Atomic Layer Deposition and Reactive Ion Etching. Using a robust process involving numerous atmospheric exposures and transport, 3D nanostructures with atomic metrology are fabricated.

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process ...

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition metal dichalcogenides (TMDs) MoS2 and WS2 can be prepared on sapphire substrates. By controlling the metal film thicknesses, good layer number controllability, down to a single layer of TMDs, can be obtained using this growth technique. Based on the results obtained from the Mo film sulfurized under the sulfur deficient condition, there are two mechanisms of (a) planar MoS2 growth and (b) Mo oxide segregation observed during the sulfurization procedure. When the background sulfur is sufficient, planar TMD growth is the dominant growth mechanism, which will result in a uniform MoS2 film after the sulfurization procedure. If the background sulfur is deficient, Mo oxide segregation will be the dominant growth mechanism at the initial stage of the sulfurization procedure. In this case, the sample with Mo oxide clusters covered with few-layer MoS2 will be obtained. After sequential Mo deposition/sulfurization and W deposition/sulfurization procedures, vertical WS2/MoS2 hetero-structures are established using this growth technique. Raman peaks corresponding to WS2 and MoS2, respectively, and the identical layer number of the hetero-structure with the summation of individual 2D materials have confirmed the successful establishment of the vertical 2D crystal hetero-structure. After transferring the WS2/MoS2 film onto a SiO2/Si substrate with pre-patterned source/drain electrodes, a bottom-gate transistor is fabricated. Compared with the transistor with only MoS2 channels, the higher drain currents of the device with the WS2/MoS2 hetero-structure have exhibited that with the introduction of 2D crystal hetero-structures, superior device performance can be obtained. The results have revealed the potential of this growth technique for the practical application of 2D crystals.

Through the sulfurization of pre-deposited transition metals, large-area and vertical 2D crystal hetero-structures can be fabricated. The film transferring and device fabrication procedures are also demonstrated in this report.

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition ...

Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model

Vanadium dioxide is a material that has a reversible metal-insulator phase change near 68 &#176;C. To grow VO2 on a wide variety of substrates, with wafer-scale uniformity and angstrom level control of thickness, the method of atomic-layer deposition was chosen. This ALD process enables high-quality, low-temperature (&#8804;150 &#176;C) growth of ultrathin films (100-1000 &#197;) of VO2. For this demonstration, the VO2 films were grown on sapphire substrates. This low temperature growth technique produces mostly amorphous VO2 films. A subsequent anneal in an ultra-high vacuum chamber with a pressure of 7x10-4 Pa of ultra-high purity (99.999%) oxygen produced oriented, polycrystalline VO2 films. The crystallinity, phase, and strain of the VO2 were determined by Raman spectroscopy and X-ray diffraction, while the stoichiometry and impurity levels were determined by X-ray photoelectron spectroscopy, and finally the morphology was determined by atomic force microscopy. These data demonstrate the high-quality of the films grown by this technique. A model was created to fit to the data for VO2 in its metallic and insulating phases in the near infrared spectral region. The permittivity and refractive index of the ALD VO2 agreed well with the other fabrication methods in its insulating phase, but showed a difference in its metallic state. Finally, the analysis of the films&#39; optical properties enabled the creation of a wavelength- and temperature-dependent model of the complex optical refractive index for developing VO2 as a tunable refractive index material.

Thin films (100-1000 &#197;) of vanadium dioxide (VO2) were created by atomic-layer deposition (ALD) on sapphire substrates. Following this, the optical properties were characterized through the metal-insulator transition of VO2. From the measured optical properties, a model was created to describe the tunable refractive index of VO2.

Vanadium dioxide is a material that has a reversible metal-insulator phase change near 68 &#176;C. To grow VO2 on a wide variety of substrates, with ...

A Fabrication and Measurement Method for a Flexible Ferroelectric Element Based on Van Der Waals Heteroepitaxy

Flexible non-volatile memories have received much attention as they are applicable for portable smart electronic device in the future, relying on high-density data storage and low-power consumption capabilities. However, the high-quality oxide based nonvolatile memory on flexible substrates is often constrained by the material characteristics and the inevitable high-temperature fabrication process. In this paper, a protocol is proposed to directly grow an epitaxial yet flexible lead zirconium titanate memory element on muscovite mica. The versatile deposition technique and measurement method enable the fabrication of flexible yet single-crystalline non-volatile memory elements necessary for the next generation of smart devices.

In this paper, we present a protocol to directly grow an epitaxial yet flexible lead zirconium titanate memory element on muscovite mica.

Flexible non-volatile memories have received much attention as they are applicable for portable smart electronic device in the future, relying on ...

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform

To form a coherent quantum transport in hybrid superconductor-semiconductor (S-Sm) junctions, the formation of a homogeneous and barrier-free interface between two different materials is necessary. The S-Sm junction with high interface transparency will then facilitate the observation of the induced hard superconducting gap, which is the key requirement to access the topological phases (TPs) and observation of exotic quasiparticles such as Majorana zero modes (MZM) in hybrid systems. A material platform that can support observation of TPs and allows the realization of complex and branched geometries is therefore highly demanding in quantum processing and computing science and technology. Here, we introduce a two-dimensional material system and study the proximity induced superconductivity in semiconducting two-dimensional electron gas (2DEG) that is the basis of a hybrid quantum integrated circuit (QIC). The 2DEG is a 30 nm thick In0.75Ga0.25As quantum well that is buried between two In0.75Al0.25As barriers in a heterostructure. Niobium (Nb) films are used as the superconducting electrodes to form Nb- In0.75Ga0.25As -Nb Josephson junctions (JJs) that are symmetric, planar and ballistic. Two different approaches were used to form the JJs and QICs. The long junctions were fabricated photolithographically, but e-beam lithography was used for short junctions&#8217; fabrication. The coherent quantum transport measurements as a function of temperature in the presence/absence of magnetic field B are discussed. In both device fabrication approaches, the proximity induced superconducting properties were observed in the In0.75Ga0.25As 2DEG. It was found that e-beam lithographically patterned JJs of shorter lengths result in observation of induced superconducting gap at much higher temperature ranges. The results that are reproducible and clean suggesting that the hybrid 2D JJs and QICs based on In0.75Ga0.25As quantum wells could be a promising material platform to realize the real complex and scalable electronic and photonic quantum circuitry and devices.

Quantum integrated circuits (QICs) consisting of array of planar and ballistic Josephson junctions (JJs) based on In0.75Ga0.25As two-dimensional electron gas (2DEG) is demonstrated. Two different methods for fabrication of the two-dimensional (2D) JJs and QICs are discussed followed by the demonstration of quantum transport measurements in sub-Kelvin temperatures.

To form a coherent quantum transport in hybrid superconductor-semiconductor (S-Sm) junctions, the formation of a homogeneous and barrier-free interface ...

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D materials is still in nascent stages, scientists cannot fully rely on traditional semiconductor techniques for related research. Delicate processes from locating the materials to electrode definition need to be well controlled. In this article, a universal fabrication protocol required in manufacturing nanoscale electronics, such as 2D quasi-heterojunction bipolar transistors (Q-HBT), and 2D back-gated transistors are demonstrated. This protocol includes the determination of material position, electron beam lithography (EBL), metal electrode definition, et al. A step by step narrative of the fabrication procedures for these devices are also presented. Furthermore, results show that each of the fabricated devices has achieved high performance with high repeatability. This work reveals a comprehensive description of process flow for preparing 2D nano-electronics, enables the research groups to access this information, and pave the way toward future electronics.

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D ...

Theoretical Calculation and Experimental Verification for Dislocation Reduction in Germanium Epitaxial Layers with Semicylindrical Voids on Silicon

Reduction of threading dislocation density (TDD) in epitaxial germanium (Ge) on silicon (Si) has been one of the most important challenges for the realization of monolithically integrated photonics circuits. The present paper describes methods of theoretical calculation and experimental verification of a novel model for the reduction of TDD. The method of theoretical calculation describes the bending of threading dislocations (TDs) based on the interaction of TDs and non-planar growth surfaces of selective epitaxial growth (SEG) in terms of dislocation image force. The calculation reveals that the presence of voids on SiO2 masks help to reduce TDD. Experimental verification is described by germanium (Ge) SEG, using an ultra-high vacuum chemical vapor deposition method and TD observations of the grown Ge via etching and cross-sectional transmission electron microscope (TEM). It is strongly suggested that the TDD reduction would be due to the presence of semicylindrical voids over the SiO2 SEG masks and growth temperature. For experimental verification, epitaxial Ge layers with semicylindrical voids are formed as the result of SEG of Ge layers and their coalescence. The experimentally obtained TDDs reproduce the calculated TDDs based on the theoretical model. Cross-sectional TEM observations reveal that both the termination and generation of TDs occur at semicylindrical voids. Plan-view TEM observations reveal a unique behavior of TDs in Ge with semicylindrical voids (i.e., TDs are bent to be parallel to the SEG masks and the Si substrate).

Theoretical calculation and experimental verification are proposed for a reduction of threading dislocation (TD) density in germanium epitaxial layers with semicylindrical voids on silicon. Calculations based on the interaction of TDs and surface via image force, TD measurements, and transmission electron microscope observations of TDs are presented.

Reduction of threading dislocation density (TDD) in epitaxial germanium (Ge) on silicon (Si) has been one of the most important challenges for the ...

Fabricating van der Waals Heterostructures with Precise Rotational Alignment

In this work we describe a technique for creating new crystals (van der Waals heterostructures) by stacking distinct ultrathin layered 2D materials. We demonstrate not only lateral control but, importantly, also control over the angular alignment of adjacent layers. The core of the technique is represented by a home-built transfer setup which allows the user to control the position of the individual crystals involved in the transfer. This is achieved with sub-micrometer (translational) and sub-degree (angular) precision. Prior to stacking them together, the isolated crystals are individually manipulated by custom-designed moving stages that are controlled by a programmed software interface. Moreover, since the entire transfer setup is computer controlled, the user can remotely create precise heterostructures without coming into direct contact with the transfer setup, labeling this technique as &#8220;hands-free&#8221;. In addition to presenting the transfer set-up, we also describe two techniques for preparing the crystals that are subsequently stacked.

In this work we describe a technique that is used to create new crystals (van der Waals heterostructures) by stacking ultrathin layered 2D materials with precise control over position and relative orientation.

In this work we describe a technique for creating new crystals (van der Waals heterostructures) by stacking distinct ultrathin layered 2D materials. We ...