[CP2K-user] Convergence problem in further steps of ab initio molecular dynamics

[Matt W]

Hi,

hybrid functional calculations using MOLOPT basis sets are extremely 
expensive. You probably need to use the Auxiliary Density Matrix Method 
approximation. See these execises 
<https://www.cp2k.org/exercises:2016_summer_school:hfx> and some slides 
<https://mattatlincoln.github.io/talks/GhentWorkshop/#/> maybe this talk 
<https://www.youtube.com/watch?v=snG4fbpI0_g&list=PLrmNhuZo9sgYJqeTWUhdhtYu3Ol988prg&index=6&t=0s>
.

Matt



On Thursday, March 28, 2019 at 8:15:26 PM UTC, Mohammad Shakiba wrote:
>
> Dear CP2K users,
>
> I have installed CP2K on our university cluster with intel 2019 and it 
> works properly for tests. However, when I use it for ab initio molecular 
> dynamics with my structure, the first 20 steps converge but the convergence 
> in the next step takes too long and it does not converge. Actually, it 
> becomes close to the convergence limit of 1.0E-6 (like 2.04E-6 which was 
> the closest) but does not converge even in outer loops and oscillates 
> between 2.0E-6 and 1.0E-4.
>
> Can you help me find out why this happens and how can I fix it? is it 
> because of my basis sets and potentials? or my structure? Is it practical 
> to increase the MAX_SCF to a high number like 1000? What are the normal 
> ranges for this limit?
>
> By the way I tried both CG and DIIS but the problem still exists.
>
> Thanks in advance.
>
> My structure contains Pb ans S atoms -> (PbS)16. Here are some main parts 
> of my attached inputs:
>
>     BASIS_SET_FILE_NAME BASIS_MOLOPT   ! I used MOLOPT bases file
>     POTENTIAL_FILE_NAME POTENTIAL          ! with GTH pseudopotentials and 
> PBE functionals
>     &MGRID
>        CUTOFF [Ry] 400
>     &END
>     &QS
>        METHOD GPW 
>        EPS_DEFAULT 1.0E-10
>        EXTRAPOLATION ASPC 
>     &END
>     &POISSON      
>       PERIODIC NONE
>       PSOLVER  MT
>     &END POISSON
>     &SCF                              
>       SCF_GUESS ATOMIC
>       MAX_SCF 400
>       EPS_SCF 1.0E-6
>       &OT
>         PRECONDITIONER FULL_SINGLE_INVERSE
>         MINIMIZER DIIS                                            ! I also 
> tried CG
>         LINESEARCH 3PNT
> !        STEPSIZE 0.08
> !        PRECOND_SOLVER INVERSE_CHOLESKY
>       &END OT
>       &OUTER_SCF                                                 ! Outer 
> SCF loop for 10 times
>         MAX_SCF 10
>         EPS_SCF 1.0E-6
>       &END
>     &XC
>       &XC_GRID
>         XC_DERIV SPLINE2
>         XC_SMOOTH_RHO NN50
>       &END XC_GRID
>       &XC_FUNCTIONAL 
>          &PBE
>          &END
>       &END XC_FUNCTIONAL
>     &END XC
>
>
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