creating a core hole with MOM
Sergey Chulkov
sergeya... at gmail.com
Thu Jun 21 13:33:11 UTC 2018
Hi Matthias,
the MOM method is simply an alternative way to occupy atomic orbitals
during SCF iterations. An excited state that you are trying to handle by
using the MOM protocol should preserve the number of electrons for every
spin channel from the ground state calculation of the given multiplicity.
In your specific case (a methane cation with its beta electron being
excited from the 1st orbital into the 5th orbital) you can achieve this by
running a conventional ground state DFT calculation for a methane cation
first:
&DFT
CHARGE 1
MULTIPLICITY 2
&SCF
SCF_GUESS atomic
# need this for the subsequent MOM calculation
ADDED_MOS 10
EPS_SCF 1.0E-7
MAX_SCF 50
&END SCF
...
&END DFT
Then you can setup the MOM calculation by adding the MOM section under your
SCF section. You need to use the molecular orbitals obtained at the
previous step as an initial guess for you MOM run:
&DFT
CHARGE 1
MULTIPLICITY 2
&SCF
SCF_GUESS restart
ADDED_MOS 10
WFN_RESTART_FILE_NAME methane_cation.wfn
EPS_SCF 1.0E-7
MAX_SCF 50
&MOM
DEOCC_BETA 1
OCC_BETA 5
&END MOM
&END SCF
...
&END DFT
It may also be useful to print the actual occupation numbers of the
molecular orbitals to be sure that your system stays at the desired excited
state during the wavefunction optimisation.
&DFT
...
&PRINT
&MO
EIGENVALUES
OCCUPATION_NUMBERS
&END MO
&END PRINT
...
&END DFT
If it is not the case, try to decrease the ALPHA parameter under the mixing
section:
&SCF
...
&MIXING
ALPHA 0.10
&END MIXING
...
&END SCF
Upon convergence CP2K saves the excited-state wavefunction into the restart
file. If you plan to do anything on top of it -- for example, to run a
molecular dynamics simulation for the molecule in this particular excited
state -- you need to set up you calculation and simply add an empty MOM
section under the SCF section. Reoccupation of the molecular orbitals is
not needed in this case because the wavefunction, which is going to be read
from the restart file, already corresponds to the target excited state.
Hope this helps,
Sergey
On Monday, June 11, 2018 at 7:25:47 PM UTC+1, Matthias wrote:
>
> Hi,
>
> I am struggling to figure out, how to correctly use the MOM method to
> specify that the carbon atom in methane should have a core hole, i.e. to
> remove one core electron from the system. When I use the following input,
> the program crashes with a segmentation fault. However, since I ran the
> test on the UK national supercomputer Archer using the default version of
> CP2K, I would be surprised if it were compiled incorrectly, + I have been
> able to run other calculations with no problems on the same system. The
> ground state calculation with the same basis set runs smoothly in no time
> at all.
>
> Any help would be greatly appreciated.
>
> Best Regards,
>
> Matthias
>
> P.S. I am aware that a similar question has been asked before, but since
> it didn't receive any responses I thought I should start a new one.
> https://groups.google.com/forum/#!searchin/cp2k/mom%7Csort:date/cp2k/JVKa3FqbUS0/_O-xtwgZAgAJ
>
>
> &GLOBAL
> PROJECT methane
> RUN_TYPE ENERGY
> PRINT_LEVEL MEDIUM
> &END GLOBAL
>
> &FORCE_EVAL
> METHOD Quickstep
> &DFT
> &POISSON
> PERIODIC NONE
> PSOLVER WAVELET
> &END POISSON
> &QS
> METHOD GAPW
> &END QS
>
> CHARGE 1
> MULTIPLICITY 2
> LSD
>
> &SCF
> MAX_ITER_LUMOS 10000
> EPS_SCF 1.0E-6
> SCF_GUESS ATOMIC
> MAX_SCF 60
> EPS_LUMOS 0.000001
> &OUTER_SCF
> EPS_SCF 1.0E-6
> MAX_SCF 6
> &END
> &MOM
> DEOCC_BETA 1
> PROJ_FORMULA SUM
> &END MOM
> &END SCF
>
> &XC
> &XC_FUNCTIONAL PBE
> &END XC_FUNCTIONAL
> &END XC
> &END DFT
>
> &SUBSYS
> &CELL
> ABC 10 10 10
> PERIODIC NONE
> &END CELL
> &TOPOLOGY
> &CENTER_COORDINATES
> &END
> &END
> &COORD
> C 0.00000010 -0.00000174 0.00000062
> H 0.97867541 0.00000198 0.49253941
> H 0.00648797 0.72060111 -0.82527843
> H -0.77313050 0.28064054 0.72381230
> H -0.21202870 -1.00124727 -0.39108047
> &END COORD
> &KIND H
> &BASIS
> 6
> 1 0 0 4 1
> 0.754732D+02 0.427821D-02
> 0.113575D+02 0.328672D-01
> 0.260081D+01 0.159578D+00
> 0.735503D+00 0.500000D+00
> 1 0 0 1 1
> 0.231761D+00 1.0000000
> 1 0 0 1 1
> 0.741675D-01 1.0000000
> 1 1 1 1 1
> 0.160000D+01 1.0000000
> 1 1 1 1 1
> 0.450000D+00 1.0000000
> 1 2 2 1 1
> 0.125000D+01 1.0000000
> &END
> POTENTIAL ALL
> &POTENTIAL
> 1 0 0
> 0.20000000 0
> &END
> &END KIND
> &KIND C
> &BASIS
> 17
> 1 0 0 7 1
> 0.272316E+08 0.979800E-06
> 0.108927E+07 0.441346E-04
> 0.871412E+05 0.784056E-03
> 0.130520E+05 0.639707E-02
> 0.297061E+04 0.333869E-01
> 0.841460E+03 0.140202E+00
> 0.274589E+03 0.500000E+00
> 1 0 0 1 1
> 0.992150E+02 1.0000000
> 1 0 0 1 1
> 0.386940E+02 1.0000000
> 1 0 0 1 1
> 0.159109E+02 1.0000000
> 1 0 0 1 1
> 0.676677E+01 1.0000000
> 1 0 0 1 1
> 0.289837E+01 1.0000000
> 1 0 0 1 1
> 0.822020E+00 1.0000000
> 1 1 1 3 1
> 0.963557E+03 0.290977E-02
> 0.148240E+03 0.568381E-01
> 0.349117E+02 0.500000E+00
> 1 1 1 1 1
> 0.108936E+02 1.0000000
> 1 1 1 1 1
> 0.419336E+01 1.0000000
> 1 1 1 1 1
> 0.171343E+01 1.0000000
> 1 1 1 1 1
> 0.735662E+00 1.0000000
> 1 0 1 1 1 1
> 0.323000E+00 1.0000000 1.0000000
> 1 0 1 1 1 1
> 0.123000E+00 1.0000000 1.0000000
> 1 2 2 1 1
> 0.520000E+01 1.0000000
> 1 2 2 1 1
> 0.135000E+01 1.0000000
> 1 2 2 1 1
> 0.520000E+00 1.0000000
> &END
> POTENTIAL ALL
> &POTENTIAL
> 4 2 0
> 0.34883045 0
> &END
> &BS
> &BETA
> L 0
> N 1
> NEL -2
> &END BETA
> &END BS
> &END KIND
> &END SUBSYS
> &END FORCE_EVAL
>
>
>
>
>
>
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