Subject: G03 ONIOM: EE Vs ME

From: "Mahesh" <mahesh.sundararajan..at..student.manchester.ac.uk>
Date: Fri, 13 May 2005 19:42:32 +0100

Dear All:
I am doing ONIOM caclulations as implemented in Gaussian 03 for copper proteins (Plastocyanin),
by polarising the QM by MM (electronic embedding) and without polarising QM the MM (Mechanical
embedding) starting from the same Input file.

For the electronic Embedding the calculation in fine. But for the Mechanical Embedding,
the calculation terminates without any error messege. 

The End of the output file looks like this.

 Fragment:  1 Trans scale: 1.0000 Rot scale: 0.0671
 NRF= 1 NRA=  66 NVA= 393 HaveQM=F
 Convergence limit is  0.300E-04 MaxStp= 19428 StMxLn= 1.00D-04 StpMin= 1.00D-06.
 Convergence criteria           0.00004500 0.00003000 0.00018000 0.00012000
  Step  NS  ND Rises OKQ   Scale  Max. Force  RMS Force Max. Disp.  RMS Disp.     Energy   Flag

   233   0   0   T    F  6.08D-01***********33.3755849548.68432575 4.10655637************* ----
   234   0   0   T    F  5.00D-01***********33.3755849529.60773135 2.49743251************* ----
   235   0   0   T    F  5.00D-01***********33.3755849514.80386568 1.24871625************* ----
   236   0   0   T    F  6.65D-01***********33.37558495 7.40193284 0.62435813************* ----
   237   0   0   T    F  5.00D-01***********33.37558495 4.92547679 0.41546736************* ----
   238   0   0   T    F  6.36D-01***********33.37558495 2.46273839 0.2077336820605.7748208 ----
   239   0   0   T    F  6.37D-01***********33.37558495 1.56563966 0.13206278 6266.8360699 ----
   240   0   0   T    F  3.16D-01***********33.37558495 0.99655472 0.08406008  -24.7516875 ----
   241   0   0   T    F  2.80D-01***********33.37558495 0.31506927 0.02657631  -30.3741662 ----
   242   0   0   T    F  2.08D-01***********33.37558495 0.08809388 0.00743078  -33.2627979 ----
   243   0   0   T    F  1.94D-01***********33.37558495 0.01835913 0.00154861  -48.6751008 ----
   244   0   0   F    F  1.26D-01***********33.37558495 0.00356823 0.00030098  -61.8162325 ----

I have minimised the structure in Amber7.0 before doing the calculation.

I think, the calculation is failing in the Micro Iteration. 

But why it is not failing in the Electronic Emedding and what is the suitable solution for this.

Thanks in Advance,

Regards,
Mahesh S