[Pw_forum] The meaning of "a" in the phonon calculation

[Lawrence Lee]

Dear all,

In the pw.x code, if I choose "calculation = phonon" calculation.
According to the INPUT_PW instruction, the xqq(1) (and 2 and 3) flags in
the namelist "&PHONON" are in the unit of 2pi/a. I would like to ask
whether that "a" is the conventional cell parameter, or the magnitude of
the primitive lattice vector?

This is important for me to know whether my specification in the
namelist "&PHONON" is correct. For example, if I want to specify a
calculation at the K point or X point. I need to know the meaning of "a"

Thanks for help very much!

-- 
S.H. Lee
Research Assistant
Physics Division
The CUHK Graduate School

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