[CP2K:10640] electrostatic decoupling

Matt W mattwa... at gmail.com
Fri Aug 17 19:42:00 CEST 2018


<Shameless advertisement>

https://aip.scitation.org/doi/abs/10.1063/1.5029818

Certainly contains a fairly good literature on the subject.

<\Shameless advertisement>

Matt


On Friday, August 17, 2018 at 3:53:56 PM UTC+1, Xiaoming Wang wrote:
>
> Hi,
>
> Thanks again.
>
> Best,
> Xiaoming Wang
>
> On Friday, August 17, 2018 at 3:34:52 AM UTC-4, jgh wrote:
>>
>> Hi 
>>
>> I am not sure, but think DDAPC suffers from the same problem. 
>>
>> regards 
>>
>> Juerg 
>> -------------------------------------------------------------- 
>> Juerg Hutter                         Phone : ++41 44 635 4491 
>> Institut für Chemie C                FAX   : ++41 44 635 6838 
>> Universität Zürich                   E-mail: hut... at chem.uzh.ch 
>> Winterthurerstrasse 190 
>> CH-8057 Zürich, Switzerland 
>> --------------------------------------------------------------- 
>>
>> -----cp... at googlegroups.com wrote: ----- 
>> To: "cp2k" <cp... at googlegroups.com> 
>> From: "Xiaoming Wang" 
>> Sent by: cp... at googlegroups.com 
>> Date: 08/16/2018 04:48PM 
>> Subject: Re: [CP2K:10640] electrostatic decoupling 
>>
>> Dear Prof. Hutter, 
>>
>> Thanks for your explanations and suggestion. I will read the 
>> corresponding papers. Btw, does the ddapc method solve 
>> this problem? There is a 'e_decpl' decoupling energy in the 
>> cp_ddapc_apply_CD. Or it still suffers the same 
>> problem? 
>>
>> Best, 
>> Xiaoming 
>>
>>
>> On Thursday, August 16, 2018 at 8:12:32 AM UTC-4, jgh wrote:Hi 
>>   
>> your problem is related to the ill-defined energy of a charge 
>> in a periodic system. 
>> Your energy 1 is calculated with a background charge to nuetralize 
>> the charge of your orbital. In energy 2, the isolated system, 
>> no such background charge is needed. 
>>   
>> If you want to get some idea how to attack this problem, I would 
>> suggest to read the vast literature on the calculation of 
>> charged defects in solids. Start with the recent work of Pasquarello. 
>>   
>> regards 
>>   
>> Juerg 
>> -------------------------------------------------------------- 
>> Juerg Hutter                         Phone : ++41 44 635 4491 
>> Institut für Chemie C                FAX   : ++41 44 635 6838 
>> Universität Zürich                   E-mail: hut... at chem.uzh.ch 
>> Winterthurerstrasse 190 
>> CH-8057 Zürich, Switzerland 
>> --------------------------------------------------------------- 
>>   
>> -----cp... at googlegroups.com wrote: ----- 
>> To: "cp2k" <cp... at googlegroups.com> 
>> From: "Xiaoming Wang"   
>> Sent by: cp... at googlegroups.com 
>> Date: 08/15/2018 10:05PM 
>> Subject: [CP2K:10631] electrostatic decoupling 
>>   
>> Hello, 
>>   
>> I'd like to decouple the the Coulomb interaction between the electron of 
>> one specific state, say HOMO,   
>> and its periodic images, for a fully periodic DFT calculation. The 
>> interested charge density is localized. 
>> I have tried to use different poisson solvers, say MT or WAVELET, to 
>> achieve my goal. So first I extracted   
>> the the charge density from mo_coeff. Then called the poisson solver. 
>>   
>> pw_poisson_solve(poisson_env, orb_rho_g%pw, ener1, v_gspace1%pw)   
>>   
>> with poisson environment PERIODIC3D. Next I changed the poisson_env to 
>> MT0D, then called  poisson 
>> solver once more. 
>>   
>> pw_poisson_solve(poisson_env, orb_rho_g%pw, ener2, v_gspace2%pw) 
>>   
>> Finally, the decoupling energy is deltaE = ener1 - ener2. I thought 
>> deltaE should be a very small 
>> number, because the charge density of that state is quite localized and 
>> my unit cell is big enough for 
>> the MT solver. However, I got a very large deltaE 0.05 Ha. Also the value 
>> is negative, which means the   
>> Hartree energy is higher for the decoupled case. I cannot understand 
>> this, because I think the image   
>> interaction would increase the energy. So can anyone give some advice? 
>>   
>> Best, 
>> Xiaoming Wang   
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