[Pw_forum] supercell contraction and cell_factor parameter

[Zhihui Zhu]

Thank you for your reply Prof. Giannozzi!
________________________________________
From: pw_forum-bounces at pwscf.org [pw_forum-bounces at pwscf.org] on behalf of Paolo Giannozzi [giannozz at democritos.it]
Sent: July 17, 2012 12:21 PM
To: PWSCF Forum
Subject: Re: [Pw_forum] supercell contraction and cell_factor parameter

On Thu, 2012-07-12 at 15:54 +0000, Zhihui Zhu wrote:

> Can anyone please explain what the cell-factor variable represent?

it represent a not-so-smart solution to a purely technical problem.
the code computes interpolation tables in reciprocal space at the
beginning of the calculation. During a variable-cell optimization,
if the cell contracts in real space, it expands in reciprocal space.
Interpolation tables extend up to cell_factor*q_max, where q_max
is what is needed at the beginning of the calculation. It does not
affect in any way the results.

P.
--
Paolo Giannozzi, IOM-Democritos and University of Udine, Italy


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