GEO_OPT and CELL_OPT difference

[sumit agrawal]

Hi everyone,

What is the difference between RUN TYPE: GEO_OPT and CELL_OPT ? Since both are doing optimization. 

Can we do GEO_OPT for crystal lattice ?

Thanks,

Sumit

[Krack Matthias (PSI)]

Yes. GEO_OPT relaxes only the atomic positions while the cell parameters are kept fixed. CELL_OPT relaxes both concurrently.

 

M.

 

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[sumit agrawal]

Thanks Matthias,

One more query: If i want to calculate binding energy for "A molecule inside the crystal lattice and a molecule on the crystal surface". Then I need to do both the operation (CELL_OPT first then GEO_OPT) or only GEO_OPT/CELL_OPT is enough?

Please let me know.

THanks ,

Sumit

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[Krack Matthias (PSI)]

Hi Sumit

 

CELL_OPT includes GEO_OPT. It is up to you if you want to relax the cell of your surface or bulk system in addition to all atomic positions.

 

M.

 

To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/CALSDoYanX8qSBv%3DyGRPdrkHxjN_mFYztrfdusb193jO5YJwCTg%40mail.gmail.com.

[sumit agrawal]

Thanks Matthias for the information. 

To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/64b03328e4b3478594d015356d6a7924%40psi.ch.

[sumit agrawal]

Hii,

Now I have done cell_opt for my 2x2x2 lattice system. I prepared an argon lattice. There will be 32 argon atoms on my lattice. Now I replace one argon atom with a CO molecule (Carbon dioxide).  I again do the cell_opt for this system.

After optimization I want to do vibrational analysis for this system. My calculation stopped when SCF started.  I don't know what I am doing wrong. Can you please suggest something?

The error message is:

SCF PARAMETERS         Density guess:                                   RESTART

                        --------------------------------------------------------
                        max_scf:                                             100
                        max_scf_history:                                       0
                        max_diis:                                              4
                        --------------------------------------------------------
                        eps_scf:                                        1.00E-06
                        eps_scf_history:                                0.00E+00
                        eps_diis:                                       1.00E-01
                        eps_eigval:                                     1.00E-05
                        --------------------------------------------------------
                        level_shift [a.u.]:                                 0.00
                        --------------------------------------------------------
                        Mixing method:                           DIRECT_P_MIXING
                        --------------------------------------------------------
                        Outer loop SCF in use
                        No variables optimised in outer loop
                        eps_scf                                         1.00E-06
                        max_scf                                               15
                        No outer loop optimization
                        step_size                                       5.00E-01
"ar31-co.out" 120L, 8381C                                                            

Here I attached my input and out files.