[Pw_forum] Conversion of alat to bhor of CELL_PARAMETERS

[Andrew Supka]

Dear Ghadiyali Mohammed Kader,

alat is what you have defined as either the parameter A or the parameter
celldm(1) under the &system namelist. celldm(1) is in bohr and A is in
angstrom.

If you have celldm(1):

multiply the entries in CELL_PARAMETERS by celldm(1)
remove the parameter celldm(1) from the &system namelist
And do CELL_PARAMETERS {bohr}

If you have A:

multiply the entries in CELL_PARAMETERS by  A*1.889725989
remove the parameter A from the &system namelist
And do CELL_PARAMETERS {bohr}

If you have neither celldm(1) or A in your &system namelist then the units
for CELL_PARAMETERS are assumed to be in bohr so then you just do:
CELL_PARAMETERS {bohr}

Andrew Supka
PhD Student - Science of Advanced Materials
Central Michigan University

On Sep 3, 2016 3:59 AM, "Mohammed Ghadiyali" <m786g at live.co.uk> wrote:

> Dear All,
>
>
> It would be very helpful if someone can inform me as how to convert or
> define a crystal structure in the combination of ibrav = 0 and
> CELL_PARAMETERS in bhor rather than the normally used combination of
> ibrav = 0 and CELL_PARAMETERS in alat.
>
>
> As I what to use phononpy for the calculation of the phonon dispersion as
> it is observed it is simpler and less expensive (computational) to use.
>
>
> Regards,
>
> Ghadiyali Mohammed Kader
>
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