Dear all,
I'm a NWChem newbie and I'm performing single point calculations on a water geometry with both NWChem and Gaussian. I'm working at the DFT level, using the BP86 exchange-correlation functional and the 6-311G* basis set. It may seem really trivial, but I can't get comparable energies (i.e. equal to the 7-8th digit) from the two programs. I also tried following the suggestions posted here: http://comp.chem.umn.edu/info/NWChem.html with little change. Here are my input files:
NWChem
title "w sp"
geometry
O 0.00000 0.00000 0.00000
H 0.92264 0.65241 0.00000
H -0.92264 0.65241 0.00000
end
charge 0
scf
singlet
rhf
end
dft
xc slater 1.0 becke88 nonlocal 1.0 perdew86 1.0 vwn_1_rpa 1.0
iterations 5000
grid lebedev 90 14 ssf euler
end
basis "ao basis" spherical
o library 6-311g*
h library 6-311g*
end
task dft
ecce_print w_dft
Gaussian
%nproc=4
# bp86/6-311g* scf=(tight) nosym integral(grid=ultrafine)
w sp
0 1
O 0.00000 0.00000 0.00000
H 0.92264 0.65241 0.00000
H -0.92264 0.65241 0.00000
The energies I get are:
NWChem : -76.600926730992
Gaussian: -76.4024349388
which are indeed very different. The same happens if I change the functional to B3LYP, even if the difference is much less dramatic.
I am probably doing something wrong but I don't understand what. Do you have any suggestions?
Thank you
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