Energy of atomic oxgyen and smearing
Matthias Krack
matthia... at psi.ch
Thu Jul 14 08:39:58 UTC 2016
Dear Natalie
for a non-periodic calculation, you have to specify "PERIODIC none" in the
&CELL *and* in the &DFT section using for instance MT as the Poisson solver
for the electrostatic decoupling:
&POISSON
PERIODIC none
POISSON_SOLVER MT
&END POISSON
which is needed for the calculation of isolated systems.
That won't solve, however, your convergence problem for the O atom. The
DIIS method employed with diagonalisation is a very efficient for SCF
convergence acceleration, but it is also very sensible to numerical noise.
That issue can be fixed by increasing the CUTOFF, e.g. from 400 to 600 Ry.
I have attached the output of such a run.
You should also keep in mind that the convergence criterion applied for
diagonalisation is different to the OT criterion. OT checks the energy
convergence whereas the largest change in a density matrix element between
two consecutive SCF steps is checked when using diagonalisation. Thus
EPS_SCF can be 10-100 times larger with diagonalisation compared to OT. An
EPS_SCF value of 1.0E-7 results in an energy convergence almost within
machine precision as you can see in the attached output.
Best regards
Matthias
On Thursday, 14 July 2016 04:05:20 UTC+2, Natalie Austin wrote:
>
> Hello Matthias,
>
> The input file is below:
>
> &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
> CHOLESKY INVERSE
> &DIAGONALIZATION
> ALGORITHM STANDARD
> &END DIAGONALIZATION
> &MIXING
> METHOD DIRECT_P_MIXING
> ALPHA 0.1 *# I also ran a case where I increased the
> value to 0.4 as you suggested. *
> 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
> MULTIPLICITY 3
> UKS .TRUE.
> &END DFT
> &SUBSYS
> &CELL
> ABC 20.00000 20.00000 20.00000
> ALPHA_BETA_GAMMA 90.00 90.00 90.00
> PERIODIC NONE
> &END CELL
> &TOPOLOGY
> COORD_FILE_NAME o.xyz
> COORDINATE XYZ
> &END TOPOLOGY
> &KIND O
> ELEMENT O
> BASIS_SET DZVP-MOLOPT-SR-GTH-q6
> POTENTIAL GTH-PBE-q6
> &END KIND
> &END SUBSYS
> &END FORCE_EVAL
> &GLOBAL
> PROJECT o
> RUN_TYPE ENERGY
> PRINT_LEVEL MEDIUM
> &END GLOBAL
> &MOTION
> &GEO_OPT
> MAX_FORCE 0.0004
> MAX_ITER 2000
> OPTIMIZER BFGS
> TYPE MINIMIZATION
> &END GEO_OPT
> &END MOTION
>
>
> and the coordinate file:
> 1
> o
> O 7.46880 7.39185 7.47705
>
>
>
> Natalie
>
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