[Pw_forum] a few frequencies in PHONON calculation

[Eduardo Menendez]

Hi everybody,

Let me insist with a question I posted two days ago.
I interpret from the manual that one can compute a few phonon irreducible
representations. If this means that one can compute a few phonon
frequencies for a big system that could be useful to do short convergence
tests. I guess these frequencies are true for a high symmetry system, but
for a low symmetry system I do not know (should I ) how  the irreducible
representations can be determined before diagonalizing the full dynamical
matrix. I have mad a test using last_irr = 10 , and then last_irr = 14, and
I get different frequencies. Maybe I do something wrong, or maybe I just do
not understand the goal of "last_irr" keyword. I appreciate that someone
kindly  clarifies this issue.

Best regards
Eduardo


Date: Tue, 22 Dec 2015 14:48:45 -0300
Subject: [Pw_forum] a few frequencies in PHONON calculation
Hi,
I have one doubt about the PHONON code. Is it possible to compute just a
few phonon frequencies using the PHONON keywords last_irr, ldiag ? For
example, using

last_irr = 10,
  ldiag=.true.,,

may one find the frequencies of just the first irreducible representations ?

Thank you,


Eduardo Menendez Proupin
Departamento de Fisica, Facultad de Ciencias, Universidad de Chile
URL: http://www.gnm.cl/emenendez

“No cometerás actos impuros ni publicarás en revistas open-acces”
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