[Pw_forum] Primitive unitcell

[Sonu Kumar]

On Wed, Oct 31, 2012 at 3:56 AM, David Furman <sirok4 at gmail.com> wrote:
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> Dear users,
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> I was reading the tutorial "From Wyckoff to Quantum Espresso" (can be found in google) to make sure how to correctly
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> write crystal input data. All examples seem to be using the primitive unit cell atomic positions (rather than the conventional unit cell). Is this actually so?
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> My question is how can I know the primitive unit cell atomic positions ?


see the International Tables for Crystallography, vol 1 or vol 2.

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> I only have conventional unit cell coordinates and 3 cell parameters for a Pnma (62) crystal.

In this case your conventional cell is primitive unit cell as Pnma is space gp.

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> Also, if I use the primitive unit cell coordinates, what value should I put to celldm(1)-celldm(3) ? is it the original conventional cell one ?
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> Many thanks,
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> David Furman
>

Regards,

SKumar
IITD

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