[Pw_forum] NEB input cell parameters

[Giuseppe Mattioli]

Dear Mitul
If I remember well you cannot perform NEB calculations in a variable-cell framework. You should choose a reasonable set of lattice parameters along 
the whole reaction path.
HTH
Giuseppe

On Thursday 06 February 2014 07:36:18 Mitul Mundra wrote:
> Hello,
> 
> I need to do NEB calculations for my system. My system consists of Si 2*2*2
> supercell with some Li impurities. Prior to NEB, I am doing a vc-relax
> calculation to get the minimum energy states for the first and the last
> images of the NEB. For the vc-relax, I set *ibrav = 1* for the symmetric
> cubic system. In the results obtained from vc-relax calculation, the cubic
> symmetry of the system is lost and I get the following call parameters for
> the initial and final state in the output file.
> 
> CELL_PARAMETERS (alat= 20.51108588)
>    1.011059885  -0.002882944  -0.000008465
>   -0.002882944   1.011059885   0.000008465
>   -0.000008492   0.000008492   1.007297719
> 
> CELL_PARAMETERS (alat= 20.51108588)
>    1.004932042   0.000000442  -0.000000442
>    0.000000442   1.004688370   0.000104290
>   -0.000000442   0.000104290   1.004688370
> 
> Now, I am confused about my input file for the NEB. I can not just directly
> change the lattice constant by taking the cube root of the new volume
> obtained. I tried to set* ibrav = 0* and give the cell parameters obtained
> but I can only enter them once (correct me if I am wrong) and thus, can not
> incorporate both the set of cell parameters. I would be extremely thankful
> if anyone could suggest me a way to tackle this difficulty.
> 
> 
> Thanks
> Mitul Mundra
> Final year Dual Degree Student
> Department of Chemical Engineering
> IIT Kanpur


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   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
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