[CP2K:9590] SCF_GUESS

[Matt W]

Assuming that the calculation converged, they might converge to different 
electronic states.

You could try and look at Mulliken spin densities or some other indicator 
to see if the solutions seem different.

Matt

On Friday, January 26, 2018 at 4:09:47 AM UTC, Xiaoming Wang wrote:
>
> Dear Prof. Hutter,
>
> I encountered the same problem again. I am doing simple ENERGY 
> calculations. I have reduced the EPS_SCF to 1.0E-8, but still the total 
> energy I obtained are different for the two cases: one is using SCF_GUESS 
> of ATOMIC, and the other is RESTART, where the restart wave function is 
> from a converged one of a similar structure with several atoms slightly 
> distorted.  Other features of my calculation are ROKS and SIC included.  I 
> am wondering why those two setups give such different results. The energy 
> difference can be as large as 0.01 Ha. Following is my input:
>
> &GLOBAL
>
>   PROJECT_NAME SS
>
>   RUN_TYPE ENERGY
>
>   PRINT_LEVEL MEDIUM
>
> &END GLOBAL
>
> &FORCE_EVAL
>
>   METHOD QS
>
>   &DFT
>
>     BASIS_SET_FILE_NAME BASIS_MOLOPT
>
>     POTENTIAL_FILE_NAME GTH_POTENTIALS
>
>     WFN_RESTART_FILE_NAME SS-RESTART.wfn
>
>     MULTIPLICITY 3
>
>     ROKS
>
>     &SIC
>
>      SIC_METHOD EXPLICIT_ORBITALS
>
>      SIC_SCALING_A 0.30
>
>      SIC_SCALING_B 0.00
>
>     &END SIC
>
>     &MGRID
>
>       CUTOFF 400
>
>       REL_CUTOFF 40
>
>     &END MGRID
>
>     &XC
>
>       &XC_FUNCTIONAL PBE 
>
>       &END XC_FUNCTIONAL
>
>     &END XC
>
>     &SCF
>
>       MAX_SCF 20
>
>       EPS_SCF 1.0e-8
>
>       CHOLESKY INVERSE
>
>       SCF_GUESS RESTART
>
>       &OT
>
>        ROTATION
>
>        PRECONDITIONER FULL_KINETIC
>
>        ENERGY_GAP 0.01
>
>        LINESEARCH 3PNT
>
>       &END OT
>
>       &OUTER_SCF
>
>        EPS_SCF 1.0e-8
>
>        MAX_SCF 50
>
>       &END OUTER_SCF
>
>     &END SCF
>   &END DFT 
>   &SUBSYS
>    ....
>    &END SUBSYS
>
> &END FORCE_EVAL
>
>
>
> Best,
> Xiaoming
>
>
> On Friday, October 27, 2017 at 4:32:51 AM UTC-4, jgh wrote:
>>
>> Hi 
>>
>> SCF_GUESS (RESTART/ATOMIC) is just for the very first guess, 
>> meaning the first SCF iteration in the first step of a MD. 
>>
>> For initial guesses within one calculation (one MD step to the 
>> next) you have to use 
>>
>> FORCE_EVAL / DFT / QS / EXTRAPOLATION  xxxxx 
>>
>> In any case, if the final result depends on any of these 
>> choices, you have another problem, e.g. your convergence criteria 
>> is not strict enough, or one calculation did not converge within the 
>> given number of steps etc. 
>>
>> regards 
>>
>> Juerg Hutter 
>> -------------------------------------------------------------- 
>> 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: 10/26/2017 05:28AM 
>> Subject: [CP2K:9590] SCF_GUESS 
>>
>> Dear all, 
>> For BAND, OPT or MD calculations, one usually sets SCF_GUESS to RESTART, 
>> which will use the WFN of the previous step as a initial guess. This will 
>> usually accelerate the convergence of the SCF loops. However, The result is 
>> different from that with SCF_GUESS sed to ATOMIC. I am confused why the 
>> final results depend on the initial guess of the wfn. 
>> Best,Xiaoming 
>>
>>
>>
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