[CP2K-user] Struggling to get SCF Convergence in Cell_Opt run

[ASSIDUO Network]

I'm going to follow your advice, but if I remember correctly, last time I 
tried smearing with 0 K, the stimulation ended with an error. If it does it 
again, I will ask for some feedback again.

On Friday, January 22, 2021 at 9:59:40 AM UTC+2 Marcella Iannuzzi wrote:

>
>
> Hi
>
> The smearing with finite electronic temperature is needed in order to 
> allow convergence of the metallic electronic structure, even if the 
> structure is kept a 0K.  The number of added MOS depends on the density of 
> states around Fermi.  Too many states do not hurt, in terms of convergence. 
> I just chose a safe number, probably less are also OK, as a lower smearing 
> temperature would also work. 
> As a functional I took one that I often use. Anyway, I think that adding 
> VDW is a good idea. 
> All these aspects are more general on electronic structure theory and not 
> specific of CP2K. Please read in the literature for better understanding.
> Regards
> Marcella
>
>
> On Friday, January 22, 2021 at 8:37:46 AM UTC+1 ASSIDUO Network wrote:
>
>> I should have added this earlier, the simulation must be performed at 0 K 
>> (my supervisor's request), it's a static run. Therefore, I cannot set the 
>> temperature to 500 K. Also, why the need for ADDED_MOS=200? In another 
>> thread, I was told that ADDED_MOS=100 was too much.
>>
>> Also, why the use of  FUNCTIONAL  XC_GGA_C_PBE and  FUNCTIONAL 
>> XC_GGA_X_RPW86? I'm new to CP2K so just want to understand everything 
>> better.
>> On Friday, January 22, 2021 at 9:24:10 AM UTC+2 Marcella Iannuzzi wrote:
>>
>>> Hi Lenard, 
>>>
>>> I got it converging in 10 iterations.
>>> The outer SCF with diagonalisation is useless, since there is no 
>>> preconditioner.
>>> With metals you need to use smearing. 
>>> Here are some settings I used:
>>>       ADDED_MOS 200
>>>       &DIAGONALIZATION T
>>>         ALGORITHM STANDARD
>>>       &END DIAGONALIZATION
>>>       &MIXING T
>>>         METHOD BROYDEN_MIXING
>>>         ALPHA 0.01
>>>         BETA 0.5
>>>         NBUFFER 8
>>>       &END MIXING
>>>       &SMEAR
>>>         METHOD FERMI_DIRAC
>>>         ELECTRONIC_TEMPERATURE 500
>>>       &END SMEAR
>>>
>>>     &XC
>>>       &XC_FUNCTIONAL
>>>           &LIBXC
>>>             FUNCTIONAL XC_GGA_X_RPW86
>>>           &END LIBXC
>>>           &LIBXC
>>>             FUNCTIONAL  XC_GGA_C_PBE
>>>           &END LIBXC
>>>       &END XC_FUNCTIONAL
>>>
>>>       &VDW_POTENTIAL
>>>        POTENTIAL_TYPE NON_LOCAL
>>>         &NON_LOCAL
>>>           CUTOFF 300
>>>           TYPE RVV10
>>> ##          VERBOSE_OUTPUT
>>>           KERNEL_FILE_NAME ${data}/rVV10_kernel_table.dat
>>>         &END NON_LOCAL
>>>       &END VDW_POTENTIAL
>>>     &END XC
>>>
>>> The results:
>>>
>>>  Step     Update method      Time    Convergence         Total energy   
>>>  Change
>>>   
>>> ------------------------------------------------------------------------------
>>>      1 NoMix/Diag. 0.10E-01   20.0     0.51067755      -133.2796876462 
>>> -1.33E+02
>>>      2 Broy./Diag. 0.10E-01   17.6     0.00064724      -136.0334243526 
>>> -2.75E+00
>>>      3 Broy./Diag. 0.10E-01   17.5     0.03257808      -134.7316158415 
>>>  1.30E+00
>>>      4 Broy./Diag. 0.10E-01   17.7     0.00019866      -133.0666478987 
>>>  1.66E+00
>>>      5 Broy./Diag. 0.10E-01   17.6     0.00228816      -133.1462861174 
>>> -7.96E-02
>>>      6 Broy./Diag. 0.10E-01   17.6     0.00032933      -133.1654553845 
>>> -1.92E-02
>>>      7 Broy./Diag. 0.10E-01   17.6     0.00000406      -133.1816175525 
>>> -1.62E-02
>>>      8 Broy./Diag. 0.10E-01   17.7     0.00009047      -133.1825852315 
>>> -9.68E-04
>>>      9 Broy./Diag. 0.10E-01   17.6     0.00000504      -133.1830490186 
>>> -4.64E-04
>>>     10 Broy./Diag. 0.10E-01   17.6     0.00000031      -133.1828944498 
>>>  1.55E-04
>>>
>>>   *** SCF run converged in    10 steps ***
>>>
>>>
>>>   Electronic density on regular grids:        -44.0000000000       
>>>  0.0000000000
>>>   Core density on regular grids:               43.9999999999       
>>> -0.0000000001
>>>   Total charge density on r-space grids:       -0.0000000001
>>>   Total charge density g-space grids:          -0.0000000001
>>>
>>>   Overlap energy of the core charge distribution:               
>>> 0.00000001219968
>>>   Self energy of the core charge distribution:               
>>> -231.41335460772382
>>>   Core Hamiltonian energy:                                     
>>> 74.19344628639691
>>>   Hartree energy:                                             
>>>  45.27318657026385
>>>   Exchange-correlation energy:                               
>>>  -21.30000506759340
>>>   Dispersion energy:                                           
>>>  0.06400174824714
>>>   Electronic entropic energy:                                 
>>>  -0.00016939092888
>>>   Fermi energy:                                                 
>>> 0.34714684334798
>>>
>>>   Total energy:                                             
>>>  -133.18289444982969
>>>
>>>
>>>
>>> Regards
>>> Marcella
>>>
>>> On Friday, January 22, 2021 at 6:48:12 AM UTC+1 ASSIDUO Network wrote:
>>>
>>>> Hi there everyone, hope you've had a great week.
>>>>
>>>> I've been trying to run a cell optimization of bulk Au, and I am using 
>>>> the attached input file, but I'm not getting an inner loop SCF convergence. 
>>>> I've made many small changes, such as including/excluding OUTER_SCF,  
>>>> changing the SCF convergence criterion, changing the number of cell 
>>>> optimization steps, changing the number of KPoints and changing the mixing 
>>>> method. Nothing has worked. I haven't tried a combination of the above 
>>>> though.
>>>>
>>>> Do you perhaps have any suggestions to me on how to get convergence? 
>>>> Furthermore, I would also appreciate some tips to speed up my simulations 
>>>> (settings/flags) wise.
>>>>
>>>> Thanks in advance,
>>>> Lenard 
>>>>
>>>>
>>>>
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