oniom calc


When we're performing oniom calcs, using G98, the calculation always crashes due to the fact that in the high-level part of the calculation the multiplicity doesn't equal the input value of 1. Looking at the output it seems that gaussian98 doesn't add the necessary terminating hydrogens.

Example we did a calculation on trifluoromethylsilane (CH3F3Si) wherein we treated the trifluoromethyl part on a medium (AM1) level whereas the rest of molecule was calculated on the High (DFT) level.

#P trackio
# opt ONIOM(B3LYP/sto-3g:AM1)
# NoSymm

oniom_test job
oniom_test archiving

0 1
SI -0.354 -0.184 0.688 High
C -1.345 -0.451 -0.882 Medium
F -1.135 -1.670 -1.475 Medium
F -2.703 -0.384 -0.701 Medium
F -1.082 0.464 -1.870 Medium
H -0.901 0.971 1.390 High
H 1.037 0.052 0.322 High
H -0.466 -1.381 1.514 High

The first AM1 calculation gives no problems but before the DFT part of the oniom calc starts for the first time the programme crashes with the following error message:

ONIOM: generating new system at layer 1
ONIOM: saving gridpoint 3
ONIOM: restoring gridpoint 9
Leave Link 120 at Tue Mar 26 12:12:02 2002, MaxMem= 6291456 cpu: 0.0
(Enter /usr/local/g98/l301.exe)
Standard basis: STO-3G (5D, 7F)
The combination of multiplicity 1 and 17 electrons is impossible.
Error termination via Lnk1e in /usr/local/g98/l301.exe.
Job cpu time: 0 days 0 hours 0 minutes 2.1 seconds.
File lengths (MBytes): RWF= 6 Int= 0 D2E= 0 Chk= 1 Scr= 1

The 17 electrons are just the silicon and the three hydrogens. Apparently the terminating hydrogen is not added by the program. Does anybody know what is going wrong here and how to fix the problem? Any suggestions are more then welcome.



 Martijn Zwijnenburg
 Lab. of Applied Organic Chemistry and Catalysis
 Delft University of Technology
 Julianalaan 136
 2628 BL Delft
 The Netherlands
 Tel: 0031-(0)152782691
 Fax: 0031-(0)152784700
 e-mail: M.A.Zwijnenburg ( ( at ) ) tnw.tudelft.nl
 web page: http://come.to/tock