Messages

1

General Questions and Answers / Re: Ab initio molecular dynamics

« on: April 23, 2017, 20:11 »

But I dont know how to obtain the forces from the  classical aproach

2

General Questions and Answers / Re: Ab initio molecular dynamics

« on: April 22, 2017, 20:35 »

Is there any tutorial for this purpose?

3

General Questions and Answers / Ab initio molecular dynamics

« on: April 21, 2017, 01:04 »

Hello

Is it possible to run ab initio molecular dynamics, and to obtains pairs (positions, forces)?


Kind regards

Javi

4

General Questions and Answers / Re: Thermal conductivity: dependence on temperature

« on: April 6, 2017, 20:01 »

No, it is the same code as the examples, but for different supercells -3x3x30, 4x4x48, 8x8x64. But I always obtain an opossite trend. This is, the conductivity increases as temperature increases, instead of decreasing

5

General Questions and Answers / Re: Thermal conductivity: dependence on temperature

« on: April 6, 2017, 18:48 »

It is PbTe (300-800K)

6

General Questions and Answers / Thermal conductivity: dependence on temperature

« on: April 6, 2017, 18:21 »

I performed simulations with the non-equilibrium Green’s function method to calculate the lattice thermal conductivity. According to my results (and the ones shown in the example), the lattice thermal conductivity increases as the temperature increases, and I dont understand why this trend happens. For most of crystals, it is usual to have a lower thermal conductivity as the temperature increases, because of the anharmonic effects. What I do is to calculate the spectrum and the obtain the thermal conductance for different temperatures.

With the reverse non-equilibrium method, the results are obtained as expected.

Could you please help me on this?

7

General Questions and Answers / Re: Lattice thermal conductivity

« on: April 6, 2017, 11:08 »

It would be because usually 4x4x1000 cells or similar are used for this purpose, but you are right when saying that it is better for me to look for a good convergence with smaller supercells.

Thanks!

8

General Questions and Answers / Lattice thermal conductivity

« on: April 5, 2017, 15:56 »

Good afternoon


I am trying to calculate the lattice thermal conductivity for a fcc crystal. I read the tutorials, and I really think that this program can be a good choice to perform these calculations. However, I would like to solve some doubts:

1.- According to the tutorials, This software allows to calculate the thermal conductivity for interfaces, but have you tested these calculations with large crystals? I imagine so. And I have tried it with small supercells -around 8x8x50 unit cells-, but I think that the software does not allows to create supercells larger than 100x100x100 - although they can be created manually. Why? Is it not necessary to use such a large supercell to obtain good results?

2.- I am a PhD student, but I would need a professional license to perform simulation in a cluster. Would I have problems with a professional license because of the different mac addresses?

Thanks a lot for your attention.


Kind regards,

Javier