[CP2K-user] Cell Optimization does not work in QM
Dr. Dirk Buddensiek
Dirk.Bu... at pc-m2.com
Thu Aug 8 09:46:18 UTC 2019
good luck. Concerning distance units: It might be that there are in Bohr
for MP2. But you can set the units explicitly in the input deck.
Am Mittwoch, 7. August 2019 17:05:56 UTC+2 schrieb Pierre-André Cazade:
> I am rather new to CP2K though I am experienced with molecular modelling
> both quantum and classical, and with a wide range of software. It is quite
> frustrating that it seems impossible to get CP2K to perform a simple
> CELL_OPT of a beta glycine crystal (20 atoms, monoclinic) with PBE. Such a
> calculation works fine with VASP, so I am quite surprised the same
> calculation goes astray with CP2K. Basically, the B unit cell vector
> increases drastically up to absurd values. Needless to say, this is a test
> system as I wish to use CP2K for its linear scaling DFT to model protein
> crystals. I have tried to play with CUTOFF and REL_CUTOFF in the MGRID
> section up to 1400 and 80 respectively. I also tried GPW and GAPW methods,
> all electrons or GTH pseudo. Nothing works. Please, if anyone could have a
> look at the attached input file "cell_opt_qm.inp" and point what's wrong in
> it, I would be grateful.
> Furthermore, I have tried LS approach with DFTB on a 5x5x5 crystal of beta
> glycine and do not have much more success. First, the pressure in the
> crystal is insanely high and will lead again to a 20 folds increase of the
> lattice vectors (with CG). Then, with LBFGS method, the system stops after
> 3 to 4 cycles with a message telling LBFGS convergence criteria were
> reached, whereas the system is clearly not. Again, I would be grateful if
> anyone could tell me what's wrong with my system ("cell_opt2_qm.inp" with
> "betacry.pdb" for the coordinates). Ideally, my goal would be to be able to
> run large complex systems with the LS approach and with any DFT/DFTB method.
> Thank you in advance for your help.
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