Energy of atomic oxgyen and smearing
Natalie Austin
natalie... at gmail.com
Thu Jul 7 19:29:41 UTC 2016
Hello,
I wanted to calculate the atomic energy of oxygen. I used the CP2K tutorial
for GEO_OPT of H2O as an example to generate the input file. What I
noticed is that the energy calculation for atomic did not converge after
500 SCF steps if I did not use smearing. Would anyone be able to explain
why this is? Because I thought for such a small atom smearing would not be
necessary. The energy for atomic oxygen also converged when I used the OT
method but I thought it best to use diagonalization to keep consistent with
the input I use for calculations on my metal systems.
This is what I believe is the relevant part of the input form the
calculation that converged. I indicated which lines were omitted from the
calculation that did not coverge:
&FORCE_EVAL
METHOD QS
&DFT
BASIS_SET_FILE_NAME BASIS_MOLOPT
POTENTIAL_FILE_NAME GTH_POTENTIALS
&MGRID
CUTOFF 400
REL_CUTOFF 60
NGRIDS 4
&END MGRID
&QS
EPS_DEFAULT 1.0E-14
MAP_CONSISTENT
&END QS
&SCF
SCF_GUESS ATOMIC
EPS_SCF 1.0E-7
MAX_SCF 500
ADDED_MOS 200 *Added MOS was
omitted in the calculation that did not converge.*
CHOLESKY INVERSE
&SMEAR ON
METHOD FERMI_DIRAC
ELECTRONIC_TEMPERATURE [K] 700 * This smear section was
omitted in the calculation that did not converge. *
&END SMEAR
&DIAGONALIZATION
ALGORITHM STANDARD
&END DIAGONALIZATION
&MIXING
METHOD BROYDEN_MIXING
ALPHA 0.1
BETA 1.5
NBROYDEN 8
&END MIXING
&END SCF
&XC
&XC_FUNCTIONAL PBE
&PBE
PARAMETRIZATION REVPBE
&END PBE
&END XC_FUNCTIONAL
&VDW_POTENTIAL
DISPERSION_FUNCTIONAL PAIR_POTENTIAL
&PAIR_POTENTIAL
TYPE DFTD3
REFERENCE_FUNCTIONAL PBE
CALCULATE_C9_TERM .TRUE.
PARAMETER_FILE_NAME dftd3.dat
R_CUTOFF 15.0
VERBOSE_OUTPUT .TRUE.
&END PAIR_POTENTIAL
&END vdw_POTENTIAL
&END XC
UKS .TRUE.
MULTIPLICITY 3
Any help with this would be appreciated.
Thanks
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