Dear NWchem community,
I ran a DFT calculation on a small molecule in solvation model using nwchem 6.8. It was converged but it has a negative frequency of about -162 cm-1. I tried to re-optimize the geometry and using a tighter energy convergence of 5d-9 but still no success.
Here is the input file:
geometry units angstroms autosym 0.2
C -0.30975950 1.32138254 0.00000000
C 0.04718087 -0.20210007 0.00000000
H 0.13238927 1.79961154 0.88134209
H -1.39114031 1.48379999 0.00000000
H 0.13238927 1.79961154 -0.88134209
O 1.27722401 -0.45562499 0.00000000
O -0.92245943 -0.99906777 0.00000000
end
basis
* library 6-311++G**
end
dft
xc b3lyp
mult 1
direct
grid fine
smear
convergence energy 5d-9 damp 45 ncydp 0 dampon 1d99 dampoff 1d-4
end
set tolguess 1d-3
driver
tight
clear
maxiter 200
end
cosmo
dielec 8.51
end
task dft optimize
task dft freq numerical
Any suggestions will greatly appreciated.
Regards,
Sophia
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