normal modes of casscf frequency analysis is in which coordinate system?

Posted by wang huan on November 05, 2008 at 07:57:03:

I am comparing the frequencies calculation results from both Molcas and Gaussian. And currently i am running into the problem that the normal mode displacements from molcas are not the same as the result from Gaussian.

Details are as follows:

I put the same geometry (same point group c2v) in both Gaussian and Molcas with same method casscf(4,4),same active space and orbital, and also the same basis set sto-3g.
In the result i can obtain almost same frequencies, however, the displacments which corresponds to each frequencies are not the same.

In molcas,

Symmetry a1
==============

1 2 3

Freq. 0.03 1911.09 4379.79

Intensity: 0.114E-11 0.129E+02 0.387E+02

H1 y 0.00000 0.56540 0.82010
H1 z 0.33324 0.77285 -0.53282
O z 0.23563 -0.06887 0.04748

In Gaussian

Low frequencies ----1084.6158 -775.4504 -730.5258 -0.0016 -0.0012 -0.0011
Low frequencies --- 1911.0606 4379.8144 4817.2010
Diagonal vibrational polarizability:
0.0000000 0.0000000 0.0000000
Harmonic frequencies (cm**-1), IR intensities (KM/Mole), Raman scattering
activities (A**4/AMU), depolarization ratios for plane and unpolarized
incident light, reduced masses (AMU), force constants (mDyne/A),
and normal coordinates:
1 2 3
A1 A1 B2
Frequencies -- 1911.0606 4379.8144 4816.5443
Red. masses -- 1.0849 1.0431 1.0868
Frc consts -- 2.3346 11.7889 14.8545
IR Inten -- 0.0000 0.0000 0.0000
Atom AN X Y Z X Y Z X Y Z
1 1 0.00 0.42 0.57 0.00 -0.59 0.38 0.00 0.58 -0.41
2 1 0.00 -0.42 0.57 0.00 0.59 0.38 0.00 0.58 0.41
3 8 0.00 0.00 -0.07 0.00 0.00 -0.05 0.00 -0.07 0.00

It is obvious that in Molcas, the A1 1911.09 cm-1 symmetry mode corresponds to the A1 1911.0606 cm-1 mode. However, the displacements are NOT the same.

At first i think this is owing to the fact that Gaussian displacements are normalized and Molcas displacements are not normalized. And it turned out that it is not normalization problem.

Then i think maybe one is mass-weighted coordinate diaplacements and the other is not. So i checked the 1911.09 cm-1 mode like this:

for H MOLCAS X 0.000 Y 0.56540 Z 0.77285
GAUSSIAN X' 0.000 Y' 0.42 Z' 0.57

then Y/Y'=SQRT(mass of H) or 1/SQRT(mass of H)
and it is obvious it is not.

So, why is the result different? And i would really appreciate that you would reply!Many thanks!

Follow Ups:

Re: normal modes of casscf frequency analysis is in which coordinate system? Roland Lindh 11:53:49 11/05/08 (0)
Re: normal modes of casscf frequency analysis is in which coordinate system? Jellby 09:56:56 11/05/08 (0)

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Comments:
: I am comparing the frequencies calculation results from both Molcas and Gaussian. And currently i am running into the problem that the normal mode displacements from molcas are not the same as the result from Gaussian. : Details are as follows: : : I put the same geometry (same point group c2v) in both Gaussian and Molcas with same method casscf(4,4),same active space and orbital, and also the same basis set sto-3g. : In the result i can obtain almost same frequencies, however, the displacments which corresponds to each frequencies are not the same. : In molcas, : Symmetry a1 : ============== : : 1 2 3 : : Freq. 0.03 1911.09 4379.79 : : Intensity: 0.114E-11 0.129E+02 0.387E+02 : : H1 y 0.00000 0.56540 0.82010 : H1 z 0.33324 0.77285 -0.53282 : O z 0.23563 -0.06887 0.04748 : : In Gaussian : Low frequencies ----1084.6158 -775.4504 -730.5258 -0.0016 -0.0012 -0.0011 : Low frequencies --- 1911.0606 4379.8144 4817.2010 : Diagonal vibrational polarizability: : 0.0000000 0.0000000 0.0000000 : Harmonic frequencies (cm**-1), IR intensities (KM/Mole), Raman scattering : activities (A**4/AMU), depolarization ratios for plane and unpolarized : incident light, reduced masses (AMU), force constants (mDyne/A), : and normal coordinates: : 1 2 3 : A1 A1 B2 : Frequencies -- 1911.0606 4379.8144 4816.5443 : Red. masses -- 1.0849 1.0431 1.0868 : Frc consts -- 2.3346 11.7889 14.8545 : IR Inten -- 0.0000 0.0000 0.0000 : Atom AN X Y Z X Y Z X Y Z : 1 1 0.00 0.42 0.57 0.00 -0.59 0.38 0.00 0.58 -0.41 : 2 1 0.00 -0.42 0.57 0.00 0.59 0.38 0.00 0.58 0.41 : 3 8 0.00 0.00 -0.07 0.00 0.00 -0.05 0.00 -0.07 0.00 : : It is obvious that in Molcas, the A1 1911.09 cm-1 symmetry mode corresponds to the A1 1911.0606 cm-1 mode. However, the displacements are NOT the same. : At first i think this is owing to the fact that Gaussian displacements are normalized and Molcas displacements are not normalized. And it turned out that it is not normalization problem. : Then i think maybe one is mass-weighted coordinate diaplacements and the other is not. So i checked the 1911.09 cm-1 mode like this: : for H MOLCAS X 0.000 Y 0.56540 Z 0.77285 : GAUSSIAN X' 0.000 Y' 0.42 Z' 0.57 : then Y/Y'=SQRT(mass of H) or 1/SQRT(mass of H) : and it is obvious it is not. : : So, why is the result different? And i would really appreciate that you would reply!Many thanks!

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