Mass-weighted nuclear hessian units

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Hello.
I just wanted some clarification for the units used for the mass-weighted nuclear hessian:

         ----------------------------------------------------
MASS-WEIGHTED 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 6.92036D-01-1.06888D-01 1.68451D+00
4 -8.03100D+00 3.66156D+00-1.17258D+00 2.98182D+01
5 3.82045D+00-2.96176D+00 5.34470D-01-1.50857D+01 1.06205D+01
6 -1.30787D+00 6.08512D-01-1.23096D+00 5.16874D+00-2.46885D+00 3.48917D+00
7 -8.10081D+00 3.83281D+00-1.30470D+00-4.98934D-01 7.43401D-01-2.33418D-01




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


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