From NWChem
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2:59:26 PM PST  Wed, Dec 16th 2015 

Hello all,
I'm trying to work with anharmonic spectra calculated by the nwchem, however, opening ecce.out I'm getting only the harmonic approximation. Do you have any idea if it is possible to get anharmonic corrections into ecce as well? If not, do you have any suggestions for a program that can read nwchem output and work with them?
I have tried also Avogadro (also version 2), but I get "could not read file" error, and Chemcraft  which recognizes only the harmonic approximation as well.
I would be grateful for any suggestions (in the longer term scale also for suggestions how to build my own code/extend the existing ones if nothing is available).
Thank you.




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6:29:47 PM PST  Sat, Dec 19th 2015 

Extending code: see the apps/scripts/parsers directory which has parser scripts in perl. See e.g. gaussian03.vib and nwchem.vib for the code that reads in frequencies.
Can you provide a short model job generating anharmonic spectral data that one could try?




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1:24:03 AM PST  Sat, Jan 9th 2016 

Sorry, I didn't see notification and then forgot about the post because of christmas... thank you for the tip, i'll check the scripts. here is the example (I ran with pair coupling with 16 grid points and it took few hours, here is diagonal coupling with only 8 grid points so it should be pretty fast):
start h2o
title "h2o anharmonic spectra"
geometry units angstroms print xyz autosym
O 1.50896 1.31694 0.00000
H 0.53896 1.31694 0.00000
H 1.83229 1.94831 0.66162
end
basis
* library 631+G*
end
dft
xc b3lyp
CONVERGENCE density 1e8
CONVERGENCE energy 1e7
GRID lebedev 99 14 ssf euler
end
cosmo
dielec 2.24
end
driver
EPREC 1e7
GRMS 0.000004
end
vscf
ngrid 8
coupling diagonal
end
ECCE_PRINT h2o.ecce.out
task dft optimize
task dft vscf



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