[Pw_forum] TD-DFT

[Stefano Baroni]

On Jan 24, 2009, at 4:47 PM, lan haiping wrote:

> Thanks for the instruction!
> Does  it mean that i should try to use BSE method to examine  
> excitons' properties?

yes (TDDFT with exact exchange would also do, though)

> I do wonder whether this failure is due to my solid systems .   My  
> basic knowledge is that tddft cannot predict proper
> optical spectra for solids system but wonderful results for isolated  
> systems due to no standard functionals for this scheme.

yes - this is the populace's (mis-) belief. the reason why TDDFT  
completely fails for excitons is exactly the same why it behaves  
(sometimes) poorly in finite systems. eg, it cannot predict Rydberg  
series. After all, what is the physical difference between an infinite  
system and a (large) finite one? shouldn't the results for the latter  
converge to those of the former when the size grows large enough?

Stefano


>
>
> Best,
> Hai-Ping
>
> On Sat, Jan 24, 2009 at 10:27 PM, Stefano Baroni <baroni at sissa.it>  
> wrote:
> ian haipin: no problem with the size of the system.
> bad news about excitons - no standard (lda/gga) implementation of  
> tddft cane ever hope to get them right (to "get them" altogether, I  
> would say)
> Stafano
>
> On Jan 24, 2009, at 10:06 AM, lan haiping wrote:
>
>> Dear Stefano & Baris:
>>
>>   I am sorry for delayed reply due to our Chinese New year holidays.
>> I feel interested in exictonic properties of tinanites' derivates,
>> and want to examine  their optical properties with TDDFT framework.
>> Though i have read some related papers include  your works on this  
>> issue,
>> i wonder about the computational load in this scheme since their  
>> relative large systems i should handle with (about 50 atoms 300  
>> electrons).
>>
>> Thanks for your help and offers.
>>
>> Best Wishes,
>>
>> Hai-Ping
>>
>>
>> On Tue, Jan 20, 2009 at 6:27 AM, Stefano Baroni <baroni at sissa.it>  
>> wrote:
>> Dear Haiping,
>>
>> please have a read at our paper first, and then revert to us with a  
>> proposal on what to do with the code. We will be glad to help with  
>> any suitable project you may have. No problem at all in writing to  
>> each other personally.
>>
>> Best regards
>> Stefano
>>
>> On Jan 19, 2009, at 9:27 PM, lan haiping wrote:
>>
>>> Dear Stefano,
>>>
>>>
>>> Is it possible for me to have a pre-public version for tddft  
>>> module of QE ?
>>> I am reading the LNP book on TDDFT, and curious about
>>> your work on this issue .
>>>
>>> Sorry for mailing you directly.
>>>
>>> Best wishes,
>>>
>>> Hai-Ping
>>>
>>> On Mon, Jan 19, 2009 at 4:25 AM, Stefano Baroni <baroni at sissa.it>  
>>> wrote:
>>> Anna: we do have an experimental code implementing TDDFT in QE,  
>>> see: J. Chem. Phys. 128, 154105 (2008). It is not yet public,  
>>> though. If you want to give it a try, please contact me or Baris  
>>> Malcioglu who is reading me in cc. Cheers - Stefano
>>>
>>>
>>> On Jan 18, 2009, at 5:04 PM, anna.ferrari at unito.it wrote:
>>>
>>>> dear all,
>>>> TD-DFT is implemented in PWSCF?
>>>> In which codes is TDDFT implemented for solids?
>>>>
>>>> thanks a lot
>>>>
>>>> anna ferrari
>>>> dip. chimica IFM
>>>> univ. Torino
>>>> _______________________________________________
>>>> 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
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
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>>>
>>>
>>>
>>> -- 
>>> Hai-Ping Lan
>>> Department of Electronics ,
>>> Peking University , Bejing, 100871
>>> lanhaiping at gmail.com, hplan at pku.edu.cn
>>
>> ---
>> 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
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> -- 
>> Hai-Ping Lan
>> Department of Electronics ,
>> Peking University , Bejing, 100871
>> lanhaiping at gmail.com, hplan at pku.edu.cn
>
> ---
> 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
>
>
>
>
>
>
>
>
>
> -- 
> Hai-Ping Lan
> Department of Electronics ,
> Peking University , Bejing, 100871
> lanhaiping at gmail.com, hplan at pku.edu.cn

---
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






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