[Pw_forum] phonon dos normalization

Mousumi Upadhyay Kahaly mousumi at jncasr.ac.in
Fri Sep 9 14:59:14 CEST 2005


Hi, I am extremely sorry for my wrong mail.

I mistook PWSCF with "Siesta" and in Siesta, following is the cause for
getting phonon FC matrix size = 2 times the total degrees of freedom.

Am really sorry,   mousumi.


> 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
> [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)
>
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