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QuantumATK => General Questions and Answers => Topic started by: lknife on May 31, 2017, 16:47

Title: which configuration is reasonable?
Post by: lknife on May 31, 2017, 16:47

Dear experts,

I built an interface using "Interface" plugin. However, after the geometry optimization, it resulted in a strange interface configuration (please see attached files), is it reasonable?
The settings for the Calculator and geometry optimization blocks are:

(1) Calculator: GGA-OMX-high,  k_point_sampling=(1, 9, 9), density_mesh_cutoff=200.0*Hartree
(2) Geometry optimization: max_forces=0.01*eV/Ang, max_stress=0.001*eV/Ang**3, disable_stress=True (constrain cell x, y, z)

Thanks very much for anyone who is willing to help me！Thank you for your time and kind help!

lknife

Title: Re: which configuration is reasonable?
Post by: lknife on May 31, 2017, 16:48

Sorry, the question should be: is the optimized interface configuration reasonable?

Title: Re: which configuration is reasonable?
Post by: Anders Blom on May 31, 2017, 18:55

That is not an interface, it's a periodic supercell

Title: Re: which configuration is reasonable?
Post by: lknife on May 31, 2017, 19:46

This job is to create an in-plane interface between Td-WTe2 and 1H-WTe2 monolayer. You can see that the left part of the unit cell is different with the right part . It's a super cell. But it's also an interface, I think. After matching the two monolayers, I wanted to relax the interface. However, the results showed me a strange configuration. I don't know if it is reasonable. 

Title: Re: which configuration is reasonable?
Post by: lknife on May 31, 2017, 19:52

For this interface configuration, it's periodic along B direction, semi-periodic along C direction and non-periodic along A direction.
When doing the geometry optimization of the interface, how to set the boundary conditions in Poison solver?

Title: Re: which configuration is reasonable?
Post by: Anders Blom on June 1, 2017, 01:58

The structure is set up as periodic in C also, and that's the problem. I refer to the many tutorials on transport systems

Title: Re: which configuration is reasonable?
Post by: lknife on June 1, 2017, 05:11

Thank you for your comment. Then could you please tell me how to set the boundary condition for this interface configuration when doing the geometry optimization?

Title: Re: which configuration is reasonable?
Post by: Anders Blom on June 1, 2017, 05:14

It's all in the tutorials, see e.g. http://docs.quantumwise.com/tutorials/device_relaxation/device_relaxation.html

Title: Re: which configuration is reasonable?
Post by: lknife on June 2, 2017, 03:12

Thank you very much! I am now reading this tutorial although I have read this tutorial before. I need to restudy it thoroughly.