Hi,
In a vibrational averaged effective geometries calculation, the dalton code calculate the entire thirdderivative tensor by numerical differentiation of the full molecular Hessian in Cartesian coordinates and after that transforming the Cartesian thirdderivative tensor to normal coordinate, but the code only writes the Cartesian thirdderivative tensor.
Can someone help me to write the thirdderivative tensor in normal coordinates in order to know which constant correspond to what set of vibrational mode indices?
Best Regards
Antonio
PS: I can calculate the thirdderivative by taking the second derivative of the molecular gradient using the .NORMAL flag, but I'm avoiding numerical instabilities
Writing thirdderivative tensor in normal coordinates

 Posts: 545
 Joined: 15 Oct 2013, 05:37
 First name(s): Peter
 Middle name(s): Robert
 Last name(s): Taylor
 Affiliation: Tianjin University
 Country: China
Re: Writing thirdderivative tensor in normal coordinates
I am not completely clear what you're asking for here. Do you want to change/extend the printout from the code to print the transformed 3rd derivatives, or do you want to look at a specific case? If the latter, it is probably easier to do it "by hand" (most likely, e.g., with a spreadsheet or with Mathematica/Maple/etc.) as a oneoff.
Best regards
Pete
Best regards
Pete

 Posts: 19
 Joined: 11 Nov 2013, 01:23
 First name(s): Antonio
 Last name(s): Arapiraca
 Affiliation: CEFET/MG
 Country: Brazil
Re: Writing thirdderivative tensor in normal coordinates
Hi Pete,
Thanks for your reply. I want to extend the printout to print the transformed 3rd derivatives. Something like that some level of print.
Thanks for your reply. I want to extend the printout to print the transformed 3rd derivatives. Something like that some level of print.

 Posts: 255
 Joined: 27 Aug 2013, 16:42
 First name(s): Kenneth
 Last name(s): Ruud
 Affiliation: UiT The Arctic University of Norway
 Country: Norway
Re: Writing thirdderivative tensor in normal coordinates
I think you can achieve such a print out by using a print level higher than 2 in *VIBANA.
Kenneth
Kenneth

 Posts: 19
 Joined: 11 Nov 2013, 01:23
 First name(s): Antonio
 Last name(s): Arapiraca
 Affiliation: CEFET/MG
 Country: Brazil
Re: Writing thirdderivative tensor in normal coordinates
Hi Kenneth,
Its works very fine. Now I'm writing the cubic force field in terms of normal modes.
Thank very much
Antonio
Its works very fine. Now I'm writing the cubic force field in terms of normal modes.
Thank very much
Antonio
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