[molpro-user] normal mode coordinates

[Jacky LIEVIN]

Dear Eryin,

the difference comes from the use or not of mass-weighted coordinates

To switch from molpro to gaussian coordinates:
1) calculate the reduced mass (mured) corresponding to the normal coordinate of interest.
mured= sum over all cartesian displacements of the square of the molpro coefficient divided by the corresponding atomic mass
Here mured = (0.14098)^2/15.99 + (0.2364)^2/12 + (0.01822)^2/31.97= 13.008
2) multiplying the molpro coeff. by sqrt(mured) gives the corresponding gaussian normal coordinate coefficient

This link may also help you: http://www.gaussian.com/g_whitepap/vib.htm
good luck

Jacky

Le 25 nov. 2010 à 16:33, Eryin Feng a écrit :

> Dear molpro user,
> 
> 
> In my work, i try to get the normal mode coordinates of a molecule by molpro, but when i compare the result get from molpro with from  Gaussian98 code, I find the different results ! 
> 
> For example:  O--C--S  (linear molecule),  V3 antisymmetry normal mode (Q3) :
> 
> in Gaussian:  Q3:  -0.50 Oz + 0.86 Cz - 0.07 Sz      ( molecule located Z axis)
> 
> in molpro:    Q3:  -0.14098 Oz + 0.2364 Cz -0.01822 Sz
> 
> 
> Can you give me some suggestions?
> 
> thanks in advance!
> 
> 
> Eryin Feng
> 
> department of physics,
> Anhui normal university,China
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_____________________________________
Prof. Jacky Liévin
Service de Chimie Quantique et Photophysique
Université Libre de Bruxelles, CPi 160/09
50 av F.D. Roosevelt
B-1050 Bruxelles
Belgium
Tel: +32-2-650 4089
Fax: +32-2-650 4232
_____________________________________