Messages

976

General Questions and Answers / Re: Pentagraphene sheet/nanotube

« on: August 16, 2017, 16:03 »

Regarding the pentagraphene, you may, in principle, use the Crystal Builder to build the pentagraphene structure, see more details on the Crystal Builder at http://docs.quantumwise.com/tutorials/crystal_builder/crystal_builder.html. In the Crystal Builder, you would be able to manually set the unit cell lattice vectors, as well as the atomic positions for carbon atoms in the unit cell. For getting all that information about the actual structure, I guess you may use some published work where the unit cell structure of pentagraphene is reported, e.g., take a look at https://www.nature.com/articles/srep22672.

977

General Questions and Answers / Re: Fitting already preapred structure into a Hexagonal Cell

« on: August 16, 2017, 13:36 »

The easiest way to build the structure of bulk InSe is to import it from the internal Database in the VNL. In the Builder, go to Add -> Database -> do a search for InSe -> add it to the Stash. I think it would be a good idea of going through our tutorials, e.g., starting with these ones:  http://docs.quantumwise.com/tutorials/getting_started.html and http://docs.quantumwise.com/tutorials/builder_manual/builder_import/builder_import.html.

978

General Questions and Answers / Re: bandgap calculation

« on: August 10, 2017, 10:19 »

Please describe what you did and what went wrong with the calculation in detail. 

979

General Questions and Answers / Re: Virtual NanoLab Error

« on: August 10, 2017, 09:16 »

Thanks for letting us know.

980

General Questions and Answers / Re: bandgap calculation

« on: August 10, 2017, 09:14 »

So, run the script with the ATK through the Job Manager or command line in the terminal.

981

General Questions and Answers / Re: length of electrode

« on: August 9, 2017, 09:04 »

In the same way as you do for old material.

982

General Questions and Answers / Re: cif file of Co2FeAl

« on: August 5, 2017, 14:50 »

You may try searching for this material in the internal and external databases available through the VNL, see http://docs.quantumwise.com/tutorials/builder_manual/builder_import/builder_import.html. If you have the material structure in a non-cif format, you could convert it to the cif format in the VNL.

983

General Questions and Answers / Re: density of states

« on: August 5, 2017, 14:44 »

Just use the 'Density of States' analysis object in the Scripter in the VNL.

984

Scripts, Tutorials and Applications / Re: atkpython has stopped working

« on: August 4, 2017, 09:41 »

If you got a license for just VNL (Graphical User Interface),  you cannot do ATK-DFT calculations, as the ATK-DFT calculator is not included, unless you order a more extended license.   

985

General Questions and Answers / Re: Young’s modulus of graphene

« on: August 3, 2017, 16:14 »

The Young's modulus value of 1.37 TPa obtained with Umberto's script seems to be consistent with that of 1.1 TPa calculated in this work posted at https://arxiv.org/abs/0906.5237.

986

General Questions and Answers / Re: Young’s modulus of graphene

« on: August 3, 2017, 14:39 »

I guess one way to figure it out by comparing to some literature values, e.g., taken from experimental or other DFT studies. So, you may google this kind of information or do searching at the Web of Science.

987

General Questions and Answers / Re: Virtual Nanolab problem

« on: August 2, 2017, 16:55 »

First, I suggest updating the ATK to 2016.4 version, as I see that you are running ATK-2016.3. Second, update AddOn plugins, using AddOn Manager in the VNL, Help->AddOn Manager. If the issue is not resolved, report it to support@quantumwise.com, but specify the operating system you are using, and what are steps you did to get the error.

988

General Questions and Answers / Re: How to set the enery cutoff ?

« on: August 1, 2017, 12:02 »

In the ATK-2017.0 version, there is a beta version of plane-wave calculator. If you want to do plane-wave (not LCAO) basis set based calculations, you may then choose ATK plane-wave calculator and set the kinetic energy cut-off, which is called Wave function cut-off in ATK.   

989

General Questions and Answers / Re: CNT Bundle

« on: July 13, 2017, 17:32 »

According to this experimental work published in APPLIED PHYSICS LETTERS 89, 133112 (2006), the answer is yes. I guess you may do a more extensive google search or searching at Web of Science to find more works on this topic.   

990

General Questions and Answers / Re: Two question about InAS p-i-n junction metal gate workfunction

« on: July 13, 2017, 15:17 »

If the work function of metal changes by applying voltage, so we can conclude that in each voltage we have a new metal. It is hard for me to accept this conclusion. If I get a wrong impression, please help me how can I correct it?

It is a matter of interpretation. In the continuum approximation, metal gate electrodes are mathematical constructs that account for boundary conditions that are to be imposed on the electrostatic potential to solve the Poisson equation.  For any metal, the macroscopic electrostatic potential should be constant inside the metal gate and on the metal gate surfaces. 

Actually, work function of real metals can be tuned by applying an external electrical field. You may think of a planar capacitor system with a non-zero electrostatic potential difference between the two identical metal plates; removing an electron from one metal plate becomes easier than for the other one, even so they are made of the same metal.

I notice, however, that I made this relation between a virtual metal gate material and real metal for the case of no gating. The virtual metal models only general dielectric property of any real metal, i.e., its response to electric field.