# CCL: conversion cart. normal modes and internal coordinates

*From*: Jan Sielk <sielk _ phc.uni-kiel.de>
*Subject*: CCL: conversion cart. normal modes and internal
coordinates
*Date*: Wed, 29 Oct 2008 16:49:18 +0100

Sent to CCL by: Jan Sielk [sielk-#-phc.uni-kiel.de]
Hello CCL users!
I have the following problem:
I want to perform a quantum dynamics calculation with a molecule in
internal coordinates (Z-matrix).
Also, I obtain normal mode coordinates (let's call them
normal_modes_xyz) with respect to the molecule in standard oriented
cart. coordinates (call them Ref_xyz) by running a frequency calculation
(using e.g. molpro).
What I need now (for some reason) is as follows:
As I change the geometry of the molecule in internal coordinates (e.g.
scaning an angle), I want to express this new geometry (named
aim_geo_zmat) as normal mode deflection. In other words, I want to know
how much I need to stretch the different normal modes to obtain my aimed
(internal coordinates) geometry. This means determine the vector "n"
in
the following equation:
Ref_xyz + n * normal_modes_xyz = new_geo_xyz
where new_geo_xyz should be equal (after conversion to a defined
Z-matrix) to aim_geo_zmat.
Does anybody know how to get the right deflection vector "n"?
Thanks in advance!
Jan
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Jan Sielk, Dipl. Chem., PhD candidate
Kiel University
Institute for Physical Chemistry
Theoretical Chemistry
email: sielk]*[phc.uni-kiel.de
homepage: http://ravel.phc.uni-kiel.de
phone: +49 431 880-1759
fax: +49 431 880-1758
mailing address:
Olshausenstr. 40
D-24098 Kiel, Germany
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