QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: atk_user on February 27, 2014, 13:16

Title: Geometry Optimization
Post by: atk_user on February 27, 2014, 13:16

Dear all,

I am try to calculate the Al unit cell with OptimizeGeometry.
However, the geometry is not changed... (Lattice parameters)
I did not consider Constrain cell and Optimizer Method is QuasiNewton, PBE functional, and DZP basis sets.

I don't know what's the problem. Could you help me?

 

Title: Re: Geometry Optimization
Post by: Umberto Martinez on February 27, 2014, 13:38

can you provide your python input script?

Title: Re: Geometry Optimization
Post by: atk_user on February 28, 2014, 02:56

Here's the input file you asked me to send you.

Thank you for your help.

Title: Re: Geometry Optimization
Post by: Umberto Martinez on February 28, 2014, 15:42

There is nothing wrong with your calculations, the job finished because it reached all the convergence criteria you set.
In particular the maximum stress criteria of 0.01 eV/Å**3.
You can check it if you include the Stress analysis in the calculation:

Code

+------------------------------------------------------------------------------+
| Stress Report                                                                |
+------------------------------------------------------------------------------+
| [[  9.05881942e-03   5.25907270e-31   7.88860905e-31]                        |
|  [  7.89246091e-31   9.05881942e-03   5.25907270e-31]                        |
|  [  5.26356654e-31   6.57319890e-31   9.05881942e-03]] eV/Ang**3             |
+------------------------------------------------------------------------------+

You should use a much lower value, something like 0.001 eV/Å**3.
See for example here this section: http://quantumwise.com/publications/tutorials/mini-tutorials/244#h3-setting-up-the-bulk-configurations (http://quantumwise.com/publications/tutorials/mini-tutorials/244#h3-setting-up-the-bulk-configurations)

Title: Re: Geometry Optimization
Post by: atk_user on February 28, 2014, 15:54

Thank you Martinez. I'll try with your suggestion.
Thank you for your help again.  :)

Have a good day.