[Pw_forum] vibrational frequencies

[Stefano Baroni]

to add my 5 cents to the thread: not all vibrational mode are IR  
active. The IR activity is what is usually nicknamed as "oscillator  
strength" of the vibrational mode, which is a linear combination of  
the ionic effective (Born) charges, the linear coefficient being  
suitable components of the vibrational eigenmode. all the necessary  
ingredients are calculated by QE. the theory can be learnt in many  
textbooks. Stefano


On Jan 19, 2009, at 2:15 AM, Axel Kohlmeyer wrote:

> for all practical purposes, there are no differences between phonons
> and infrared frequencies. axel.
>
> On 1/18/09, Jonas Baltrusaitis <jasius_1 at yahoo.com> wrote:
>> I see the problem now. I am so used to calculating Hessian upon  
>> each atom
>> displacement in non-plane wave type calculations. Are there any  
>> examples on
>> how to setup calculations to eventually get IR frequencies?
>>
>> JOnas
>>
>>
>> --- On Sun, 1/18/09, j.antonio.montoya at gmail.com
>> <j.antonio.montoya at gmail.com> wrote:
>>
>>> From: j.antonio.montoya at gmail.com <j.antonio.montoya at gmail.com>
>>> Subject: Re: [Pw_forum] vibrational frequencies
>>> To: jasius_1 at yahoo.com, "PWSCF Forum" <pw_forum at pwscf.org>
>>> Date: Sunday, January 18, 2009, 3:23 PM
>>> Dear Jonas,
>>>
>>> From the phonon calculation you can automatically get the
>>> IR and Raman active frequencies, and with a bit more of
>>> effort also the intensities.
>>>
>>> If you don't know the relation between phonons and the
>>> frequencies you are looking for, please read a book on solid
>>> state physics, or in IR spectroscopy.
>>>
>>> Javier Montoya
>>> CIW, DC 20015
>>> USA
>>> Sent via BlackBerry by AT&T
>>>
>>> -----Original Message-----
>>> From: Jonas Baltrusaitis <jasius_1 at yahoo.com>
>>>
>>> Date: Sun, 18 Jan 2009 14:27:29
>>> To: PWSCF Forum<pw_forum at pwscf.org>; lan
>>> haiping<lanhaiping at gmail.com>
>>> Subject: Re: [Pw_forum] vibrational frequencies
>>>
>>>
>>> Well, I did my homework but couldn't find anything
>>> about calculating vibrational frequencies (infrared
>>> spectrum). Only phonon frequencies... IAny clues?
>>>
>>> JOnas Baltrusaitis
>>> University of IOwa
>>>
>>>
>>> --- On Sat, 1/17/09, lan haiping
>>> <lanhaiping at gmail.com> wrote:
>>>
>>>> From: lan haiping <lanhaiping at gmail.com>
>>>> Subject: Re: [Pw_forum] vibrational frequencies
>>>> To: jasius_1 at yahoo.com, "PWSCF Forum"
>>> <pw_forum at pwscf.org>
>>>> Date: Saturday, January 17, 2009, 9:40 PM
>>>> Hi,
>>>> Please take a look at www.quantum-espresso.org or the
>>>> userguide along with
>>>> the QE package.
>>>> A simple answer is "Yes"!
>>>>
>>>> And please supply your affiliation!
>>>>
>>>> best
>>>>
>>>> On Sun, Jan 18, 2009 at 1:36 PM, Jonas Baltrusaitis
>>>> <jasius_1 at yahoo.com>wrote:
>>>>
>>>>> Can pwscf calculate vibrational frequencies
>>> (IR)?
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Pw_forum mailing list
>>>>> Pw_forum at pwscf.org
>>>>>
>>> http://www.democritos.it/mailman/listinfo/pw_forum
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Hai-Ping Lan
>>>> Department of Electronics ,
>>>> Peking University , Bejing, 100871
>>>> lanhaiping at gmail.com, hplan at pku.edu.cn
>>>
>>>
>>>
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
>>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
>>
>>
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
>>
>
>
> -- 
> = 
> ======================================================================
> Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http:// 
> www.cmm.upenn.edu
>  Center for Molecular Modeling   --   University of Pennsylvania
> Department of Chemistry, 231 S.34th Street, Philadelphia, PA  
> 19104-6323
> tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
> = 
> ======================================================================
> If you make something idiot-proof, the universe creates a better  
> idiot.
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum

---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
http://www.sissa.it/~baroni / [+39] 040 3787 406 (tel) -528 (fax) /  
stefanobaroni (skype)

La morale est une logique de l'action comme la logique est une morale  
de la pensée - Jean Piaget

Please, if possible, don't  send me MS Word or PowerPoint attachments
Why? See:  http://www.gnu.org/philosophy/no-word-attachments.html






-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20090119/d26362ae/attachment.html>