# CCL:G: ONIOM Optimization

• From: "Ajanta Deka" <ajanta[]tezu.ernet.in>
• Subject: CCL:G: ONIOM Optimization
• Date: Mon, 13 Jul 2009 08:10:23 -0400

``` Sent to CCL by: "Ajanta  Deka" [ajanta*tezu.ernet.in]
Dear All,
I am trying to do an optimzation using ONIOM method (Gaussian 03)for
faujasite zeolite. For the QM part I am using uB3LYP/6-31g(d,p) and
uB3LYP/LanL2dz and UFF for the MM part. I observe something strange in the
output. When I look at the energy values in the subsequent steps of
optimization, this is what I find
SCF Done:  E(UB+HF-LYP) =  -2190.15693744     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15700719     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15693744     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15700718     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15693745     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15700721     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15693745     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15700720     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15693744     A.U. after   24 cycles
SCF Done:  E(UB+HF-LYP) =  -2190.15700718     A.U. after   24 cycles
Thus, the energy is approaching two different values.
Ultimately, the job fails with the following messaqe
Error termination request processed by link 9999.
Error termination via Lnk1e in /home/ramesh/g03/l9999.exe at Sat Jul 11
18:01:11 2009
Job cpu time:  6 days 21 hours 53 minutes  6.0 seconds.
File lengths (MBytes):  RWF=    100 Int=      0 D2E=      0 Chk=     20
Scr=      1
I have tried by changing the initial geometry slightly, but I get the same
result. I have successfully got the optimized geometry for a similiar
system (with slightly different charge). I do not know how to overcome