From owner-chemistry@ccl.net Tue Oct 29 02:39:01 2024
From: "Grigoriy Zhurko reg_zhurko[]chemcraftprog.com" <owner-chemistry===server.ccl.net>
To: CCL
Subject: CCL:G: Printing the Hessian in Orca output files
Message-Id: <-55235-241029022507-14729-/CNABjWP+3T+vqJhpMnUOQ===server.ccl.net>
X-Original-From: Grigoriy Zhurko <reg_zhurko|chemcraftprog.com>
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Date: Tue, 29 Oct 2024 09:24:56 +0300
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Sent to CCL by: Grigoriy Zhurko [reg_zhurko-$-chemcraftprog.com]
I am implementing the computation of vibrational frequencies in RRHO approximation in my program (this can be useful for quick computation of the kinetic isotope effects). My program can read a Gaussian .fch file with the Hessian, and compute the frequencies. My question is, how can I enable the printout of the Hessian in Orca output files, and also in the output files produced by other QC packages (Gamess, Molpro, NWChem, etc).

Maybe somebody can send here some samples of Gamess/Molpro files with a hessian and frequencies, and I will implement the frequencies computation and verify it with these files.

And one more question: how difficult is to compute the Hessian if I have only the frequencies and normal modes. More exactly, I mean the frequencies except the 6 translational/rotational ones, as only they are usually printed in the output files. Also, maybe the printout of the translational/rotational frequencies in the output files can be enabled?

Grigoriy Zhurko
https://chemcraftprog.com