Hello
Say I have a 19 atom Pt cluster, which has 190 electrons in total (10 electrons per Pt). Correspondingly, there are 19*5=95 d-orbital of Pt. I want to fill these 95 d-orbitals with 95 up-spin electrons and 81 down spin electrons. Remaining 14 electrons go into seven of the 6s levels. Besides, the LANL2DZ_ecp basis set that I am using offers 18 electrons as valence electrons for Pt. However, I want to only fix the earlier mentioned 5d electronic occupations. How can I deal with this problem using OCCUP/or any other keyword? I tried mult keyword however, upon energy minimization the occupations do not stay fixed to the set values (refer below).
I also read in this forum that OCCUP keyword can only be used with single point energy calculations. Which restricts my future calculations of adsorbates on this Pt cluster as I require geometry optimization for the adsorbates. Any hints on how to go about my problem of fixing occupation?
Thank you.
Test calculation with 6 atom Pt system and occupations corresponding to energy minimum:
MULT=3
Occupations of the irreducible representations
----------------------------------------------
irrep alpha beta
-------- -------- --------
ag 27.0 27.0
au 27.0 27.0
MULT=5
Occupations of the irreducible representations
----------------------------------------------
irrep alpha beta
-------- -------- --------
ag 27.6 26.2
au 27.2 27.0
MULT=7
Occupations of the irreducible representations
----------------------------------------------
irrep alpha beta
-------- -------- --------
ag 28.0 24.0
au 29.1 26.9
MULT=9
Occupations of the irreducible representations
----------------------------------------------
irrep alpha beta
-------- -------- --------
ag 28.0 24.0
au 29.1 26.9
Input file:
echo
geometry autosym
Pt -0.831261 -0.804522 -1.403607
Pt -0.831261 -0.804522 1.403607
Pt -0.822937 -3.235626 0.000000
Pt 1.458032 0.013694 0.000000
Pt 1.466355 -2.417410 -1.403607
Pt 1.466355 -2.417410 1.403607
end
basis "large" cartesian
Pt library lanl2dz_ecp file /usr/local/NWChem/data/libraries/
end
ecp
Pt library lanl2dz_ecp file /usr/local/NWChem/data/libraries/
end
set "ao basis" "large"
dft
iterations 1000
direct
mult 3
XC xpbe96 cpbe96
convergence ncyds 1000 damp 70 ncydp 500 diis 16
smear 0.001
end
DRIVER
XYZ a.xyz
MAXITER 500
END
task dft energy
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