Re: Gaussian ONIOM problem

["Phil Hultin" <hultin-0at0-cc.UManitoba.CA>]

Martijn Zwijnenburg inquired about the failure of an ONIOM calculation
 using
 G98.  I just encountered the same problem with my first attempts at using
 ONIOM.
 I found that it was necessary to explicitly define the "replace-atom"
 in the
 input file for those atoms which were at the boundary between higher and
 lower levels.  The Gaussian manual states that defining a replace-atom is an
 option, but this apparently is NOT the case.
 So, Martijn, try modifying your input file to this:
 %Chk=oniom_test
 #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  H
 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
 Dr. Philip G. Hultin
 Associate Department Head and
 Associate Professor of Chemistry
 University of Manitoba
 Winnipeg, MB, Canada R3T 2N2
 (vox) 204-474-9814
 (fax) 204-474-7608
 mailto:hultin-0at0-cc.umanitoba.ca
 http://www.umanitoba.ca/chemistry/