[CP2K-user] [CP2K:13668] SCAN XC density functional: Do we have to use specific PSEUDOPOTENTIALS for SCAN? Are they available?

[Vyacheslav Bryantsev]

Thank you, Thomas,
I wanted to check that it is safe to use these non-default options for 
production calculations, as long as the density cutoffs are reasonable.

Slava


On Monday, July 27, 2020 at 1:54:21 AM UTC-4, tkuehne wrote:
>
> Dear Vyacheslav and Tian, 
>
> the usage of post-GGA functionals involves the calculation of \nabla n 
> and nasty derivatives of the form \partial e^{XC} / \partial \nabla n, 
> which gives rise to strong so-called „ringing effects“. 
> To avoid the latter a number of smoothing operators such as NN10, 
> SPLINE3, etc. are provided, whose numerical derivatives assume less 
> continuity. Many of these smoothing operators also have a favorable 
> convergence behavior wrt to the density cutoff, which otherwise would 
> require rather high values to filter out the highest frequencies. 
>
> Greetings, 
> Thomas
>
> Am 27.07.2020 um 03:56 schrieb Vyacheslav Bryantsev <
> vyac... at gmail.com <javascript:>>:
>
> Dear Tian and CP2K developers,
>
> I confirm for my system, which is a concentrated  aqueous salt, these 
> options work with  CUTOFF=800 and it would probably work at smaller values 
> also.
>
>         &XC_GRID
>
>                XC_DERIV NN10_SMOOTH
>
>                XC_SMOOTH_RHO NN10
>         &END XC_GRID
> Interestingly, removing them requires CUTOFF of at least 1200.
> A question to developers: What do these parameters do and what do those 
> specific options mean?
> There is very little information in the manual about these options.
>
> Thank you
> Slava
> Vyacheslav Bryantsev
>
> On Thursday, June 4, 2020 at 6:22:38 AM UTC-4, Hua Tian wrote:
>>
>> Dear Prof. Hutter and Bryantsev,
>> In my FPMD simulations for aqueous solutions by using SCAN functional 
>> (with the MOLOPT-SR basis sets and the GTH  pseudopotentials for SCAN from 
>> the website in your e-mail.), I found that smoothing methods (e.g., 
>> &XC_GRID / XC_DERIV NN10_SMOOTH / XC_SMOOTH_RHO NN10 / &END XC_GRID) was 
>> probably important for the convergence of SCF. For a simulation using SCAN 
>> functional with CUTOFF 400 that SCF did not converge, adding the &XC_GRID 
>> part methoned above made the SCF converge. However, I did not know if this 
>> setting would influence the accuracy of simulations.
>> Sincerely, 
>> Tian Hua
>>
>>
>> 在 2020年4月10日星期五 UTC+8下午6:31:42，jgh写道：
>>>
>>> Hi 
>>>
>>> 1) Many people have used PBE pp previously. 
>>>    SCAN optimized pp can be found at 
>>>    https://github.com/juerghutter/GTH/blob/master/SCAN/POTENTIAL 
>>> 2) Newly published SCAN parameters for D3 are available in the current 
>>>    version of CP2K from Github. For older version you need to 
>>>    add a line in the input with the parameters. 
>>> 3) Use very high cutoffs, depending on your system. If the cutoff is not 
>>>    high enough SCF will not converge smoothly to a low value (10^-7 in 
>>> OT). 
>>>    I don't have experience if the smoothing methods work to reduce the 
>>> cutoff. 
>>>
>>> regards 
>>>
>>> Juerg Hutter 
>>> -------------------------------------------------------------- 
>>> Juerg Hutter                         Phone : ++41 44 635 4491 
>>> Institut für Chemie C                FAX   : ++41 44 635 6838 
>>> Universität Zürich                   E-mail: h... at chem.uzh.ch 
>>> Winterthurerstrasse 190 
>>> CH-8057 Zürich, Switzerland 
>>> --------------------------------------------------------------- 
>>>
>>> -----c... at googlegroups.com wrote: ----- 
>>> To: "cp2k" <c... at googlegroups.com> 
>>> From: "Vyacheslav Bryantsev" 
>>> Sent by: c... at googlegroups.com 
>>> Date: 04/09/2020 04:50PM 
>>> Subject: [CP2K:13100] SCAN XC density functional: Do we have to use 
>>> specific PSEUDOPOTENTIALS for SCAN? Are they available? 
>>>
>>> Dear CP2K Community, 
>>>
>>> Is there a set or recommended setting for using SCAN in cp2k? 
>>>
>>> More specifically, 
>>> 1. Can we use PBE pseudopotentials for SCAN or this is a bad idea? If 
>>> not, where one can find specific pseudopotentials reparametrized for SCAN? 
>>> 2. Does the D3 correction work automatically now with SCAN. If not, how 
>>> to specify it? 
>>> 3. Recommendations for grid when using SCAN 
>>>
>>> Thank you, 
>>> Slava   
>>>
>>>
>>>   
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>>>   
>>>
>>
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>
> ==============================
> Thomas D. Kühne
> Dynamics of Condensed Matter
> Chair of Theoretical Chemistry
> University of Paderborn
> Warburger Str. 100
> D-33098 Paderborn
> Germany
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