回复： [CP2K:4204] SCF Convergence

[shoutian sun]

Hi SeokYun,

I have some suggestions for your input file.
 
1. The conformer you used for optimization is very poor, even using atomic unit,
    the C-C distance of the ring is about 3.33 anstrom (kinds be wrong) or 3.33 bohr 
    (about 1.76 angstrom, also a bit larger, isn't it?).  So, my suggestion is rebuilding
    your conformer.
 
2. use the POISSON_SOLVER (I think your systerm is a cluster, right?)
    &POISSON
         PERIODIC none
         POISSON_SOLVER wavelet
    &END POISSON

3. use  MINIMIZER CG for OT sec. (If SCF doesn't converge, sometimes, it works)
 
4. XC_FUNCTIONAL Pade is not a good choice. (BLYP, I always used.)
 
5. sometime, SCF doesn't converge, you have to use smooth method in the &XC section
    , as follows:
      &XC_GRID 
         XC_SMOOTH_RHO NN10
         XC_DERIV SPLINE2_SMOOTH
      &END XC_GRID 

6. cell parameter:      ABC 40.000 40.000 40.000
    I think the default unit is angstrom, right?
    40.0 angstrom for 35 atoms conformer is quite big.
    And very time consuming, Don't you think so?
    (PERIODIC none for clusters.)
 
7. The coordinates of your conformer. I think your comformer
    is build in atomic unit. And you do not modify it and just put
    it in the &COORD.....&END COORD section. Am I right?
    However, the problem is the default unit of atom coordinates
    for cp2k is angstrom, not bohr. So, please modify it, or add
    key word: UNIT Bohr in the following sec.
 
    &COORD
        C    15.02103029        21.43572257     20.18000314
        C    12.13797029        19.86029257     20.10217314
            ..................
       &END COORD
 
8. using POISSON_SOLVER wavelet, you have to use the following key words
    to put the cluster in the center of the box.
 
    &TOPOLOGY
        &CENTER_COORDINATES 
        &END
    &END 

 
I rebuild your comformer and do the optimization with my input file, it converge well.
For detail, please refer to cp2k input reference.
 
Hope, it works for you.
 
Regards,
sun
Chemistry, CUHK, Hong Kong
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