CCL:G: Hessian Matrix in Internal Coordinates

• From: Andrea Coletta <andrea_coletta**libero.it>
• Subject: CCL:G: Hessian Matrix in Internal Coordinates
• Date: Sun, 23 Nov 2008 17:33:33 +0100

``` Sent to CCL by: Andrea Coletta [andrea_coletta,,libero.it]
```
Hi, i'm trying to obtain the Hessian Matrix output in Internal Coordinates, from a B3LYP Optimization job with Gaussian03.C02.
``` My route section is:
#P B3LYP/6-31G* OPT=CalcAll SCRF=CPCM
```
if I use this with a small molecule (e.g Water), in the log file I find something like:
``` (Enter /apps/GEN03.C02/g03/l103.exe)
Berny optimization.
Internal  Forces:  Max     0.000010959 RMS     0.000006781
Search for a local minimum.
Step number   4 out of a maximum of  20
All quantities printed in internal units (Hartrees-Bohrs-Radians)
Second derivative matrix not updated -- analytic derivatives used.
Trust test= 1.00D+00 RLast= 3.53D-03 DXMaxT set to 4.24D-01
The second derivative matrix:
R1        R2        A1
R1           0.46509
R2          -0.00302   0.46509
A1           0.02978   0.02978   0.16989
Eigenvalues ---    0.16394   0.46802   0.46812
RFO step:  Lambda= 0.00000000D+00.
and this is exactly what I want!
It works also with an HF Opt test-job I did with Glycine:
#P HF/3-21G OPT=(ModRedundant,CalcAll) SCRF=pcm
[...]
Force constants in Cartesian coordinates:
1             2             3             4             5
1  0.809587D+00
2  0.000000D+00  0.790299D+00
3  0.137405D-01  0.000000D+00  0.642144D+00
4 -0.114527D+00  0.000000D+00 -0.475510D-02  0.644272D+00
```
5 0.000000D+00 -0.110951D+00 0.000000D+00 0.000000D+00 0.621385D+00 6 0.118871D-01 0.000000D+00 -0.243725D+00 -0.379120D-02 0.000000D+00
``` [...]
Force constants in internal coordinates:
1             2             3             4             5
1  0.426378D+00
2  0.122242D-01  0.472234D+00
3  0.115444D-01  0.547739D-02  0.471563D+00
4  0.115444D-01  0.547739D-02  0.574356D-02  0.471563D+00
```
5 0.138575D-01 -0.102523D-02 -0.441368D-02 -0.441368D-02 0.404944D+00 6 0.737045D-02 0.195704D-03 0.204429D-03 -0.726729D-03 0.548064D-02
` `
This is very good... the only difference is that it does'nt specify the internal coordinate, and it wrote the Matrix just before enthering l103.exe... rather than just after entering, like in the Water calculation...
` `
When I try with another molecule a little greater (33 Atoms) it does'nt work!!, It does'nt print in the log the Hessian matrix, and in the fchk I find only the Hessian Matrix in Cartesian coordinates...
` `
I use use the same Route section, and i've tried a lot of other combinations but nothing's working!
``` #P B3LYP/6-31G* OPT=CalcAll SCRF=CPCM
or
#P B3LYP/6-31G* OPT=(Redundant,CalcAll) SCRF=CPCM
or
#P B3LYP/6-31G* OPT=(ModRedundant,CalcAll) SCRF=CPCM
or
#P B3LYP/6-31G* OPT=CalcFC
etc. etc.
```
Maybe the problem is that my system has too many internal degree of freedom (96)?
``` Any Suggestions?
Thanks
*****************************
Andrea Coletta
University of "Tor Vergata"
Rome - Italy
*****************************
```