[Pw_forum] phonon dos normalization

[Stefano Baroni]

On Sep 9, 2005, at 12:42 PM, Mousumi Upadhyay Kahaly wrote:

> Hi,
>
> In order to cancel first order errors in d/dx form,
> and to get better results, each atom is once displaced by
> +delta and then by -delta. Then Dynamical matrices are
> calculated. Hence matrix size= 2 times the total degrees
> of freedom, i.e. twice what you expect.

???

May I suggest that only people who i) unrerstand questions and ii)  
know sensible answers provide the latter?

SB


>
> regards.
>
>
>
>> Dear PW users,
>>
>> After several testing, I found that the phonon density
>> of state from the PWscf calculations are normalized to
>> six times the number of atoms in a unit cell. That is
>> twice of the degrees of freedom. I wonder why don't we
>> just normalize it to the degrees of freedom or just to
>> one?
>>
>> I would appreciate it very much if someone could give
>> me an explanation.
>>
>> W. YU
>>
>>
>>
>>
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>
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
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