[Pw_forum] Frequency and zero point energy

[oulihui666]

Dear Gabriele Sclauzero, 
  Thank you for your help. 
Best regards
Lihui


--

======================================
Lihui Ou
PH.D Candidate in Electrochemistry                      
College of Chemistry and Molecular Science            
Wuhan University,430072,Hubei Province,China 
E-mail:oulihui666 at 126.com
======================================
>Date: Mon, 24 Aug 2009 08:45:32 +0200
>From: Gabriele Sclauzero <sclauzer at sissa.it>
>Subject: Re: [Pw_forum] Reply (was Frequency and zero point energy
> calculations)
>To: PWSCF Forum <pw_forum at pwscf.org>
>Message-ID: <4A92370C.6040106 at sissa.it>
>Content-Type: text/plain; charset=utf-8; format=flowed
>
>
>Dear Lihui,
>
>    I have an update to this answer: for phonon calculations based on data produced by 
>pw.x using gamma point tricks (i.e. K_POINTS GAMMA), you should use the code phcg.x in the 
>Gamma/ directory, not ph.x.
>
>regards,
>
>GS
>
>Gabriele Sclauzero wrote:
>> Dear Lihui,
>> 
>> oulihui666 wrote:
>>> Dear Gabriele Sclauzero,
>>>   I am intend to calculate the frequency of CO2 molecule, so I should 
>>> perform scf calculation at first, when setting k points as gamma, it 
>>> will appear a error in the process of calculating frequency, as follows:
>>> ***********************************************************************
>>> from phq_readin. error #1
>>> cannot start from pw.x data file using Gamma-point tricks
>>> ***********************************************************************
>> 
>>  From what I can understand, this does not mean that you cannot do the calculation for the 
>> Gamma point only, but rather that the calculation cannot be done using Gamma 
>> point-specific algorithms (which are much faster than the general ones).
>> You should anyway be allowed to do the calculation using
>> K_POINTS AUTOMATIC
>> 1 1 1  0 0 0
>> which builds a k-point grid containing the Gamma point only, but does not use Gamma-point 
>> tricks.
>> 
>> You can do the relaxations (and all other expensive pw calculations) using
>> K_POINTS GAMMA
>> and then, starting from the optimized atomic positions, do a nscf run using
>> K_POINTS AUTOMATIC
>> 1 1 1  0 0 0
>> before the phonon run.
>> 
>> Cheers
>> 
>> GS
>> 
>> P.S: please avoid private mails and stick to the thread you started in the forum, so that 
>> anyone can help and know when your problem has been solved. Thanks!
>> 
>> 
>> 
>>> So I do not set k point as gamma in scf calculation.
>>>  
>>>  Best regards
>>>  Lihui 
>>>
>>> --
>>> ======================================
>>> Lihui Ou
>>> PH.D Candidate in Electrochemistry                     
>>> College of Chemistry and Molecular Science           
>>> Wuhan University,/430072/,Hubei Province,China 
>>> /E-mail:oulihui666 at 126.com <mailto:oulihui666 at 126.com>/
>>> ======================================
>>>
>>>
>>> ------------------------------------------------------------------------
>>> ???????????,www.yeah.net <http://www.yeah.net/?from=footer>
>> 
>
>-- 
>
>
>o ------------------------------------------------ o
>| Gabriele Sclauzero, PhD Student                  |
>| c/o:   SISSA & CNR-INFM Democritos,              |
>|        via Beirut 2-4, 34014 Trieste (Italy)     |
>| email: sclauzer at sissa.it                         |
>| phone: +39 040 3787 511                          |
>| skype: gurlonotturno                             |
>o ------------------------------------------------ o
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