From NWChem
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10:32:26 AM PST  Thu, Feb 20th 2014 

Hello.
I just wanted some clarification for the units used for the massweighted nuclear hessian:

MASSWEIGHTED NUCLEAR HESSIAN (Hartree/Bohr/Bohr/Kamu)

1 2 3 4 5 6 7 8 9 10
    
1 4.70295D+00
2 1.83038D+00 2.19102D+00
3 6.92036D011.06888D01 1.68451D+00
4 8.03100D+00 3.66156D+001.17258D+00 2.98182D+01
5 3.82045D+002.96176D+00 5.34470D011.50857D+01 1.06205D+01
6 1.30787D+00 6.08512D011.23096D+00 5.16874D+002.46885D+00 3.48917D+00
7 8.10081D+00 3.83281D+001.30470D+004.98934D01 7.43401D012.33418D01
The output file says the units are Hartree/Bohr/Bohr/Kamu, so does this mean the hessian is divided by 1000*amu? I am trying to calculate the force constants from the massweighted nuclear hessian so I am wondering whether I need to multiply the values by 1000 and the atomic masses to get the force constants or whether I need to divide by 1000 and multiply by amu.
Also, I know Gaussian09 provides the force constant matrix in the output file, and was wondering whether there is a keyword I can use in NWChem to also get the force constant matrix.
Thank you in advance for your time and help!
Sandy Fernando




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8:35:33 AM PDT  Fri, May 9th 2014 

The force constant matrix can be found in the file *.hess in lower triangular form.



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