[molpro-user] Problem with t2 Norm in MP2 calculations

Christof Woell woell at pc.ruhr-uni-bochum.de
Tue Sep 28 07:33:05 BST 2004

Problem with t2 Norm in MP2 calculations

I am doing MP2 calculations for a rather large system, a hydrocarbon on top 
of a metal cluster.
When computing the potential vs. distance curves everything works fine for 
large distances.
When the distance gets smaller,  I get on the MP2-level the following 
errror message:
  Multipassing necessary in transformation. To avoid, increase memory 
by    3195515025 words
  Integral transformation finished. Total CPU:******* sec, 
npass=  5  Memory used: 979.16 MW
  Memory needed for MP2:                       1.13 MW
  Norm of t2 vector:     53.77169283      P-energy:    -3.32278637
  Reference energy                   -1303.594849374982
  Correlation energy                    -3.322786371429
  !MP2 ENERGY                        -1306.917635746411

At the same time, the SCF-calculations converges fine. When I decrease the 
distance further, the t2-norm gets even larger.
Does anyone have an idea? Could this arise from linear dependencies in the 
basis set?

Any advice will be appreciated. Thank you.

Christof Wöll

Prof. Dr. Christof Wöll
Physikalische Chemie I, Ruhr-Universitaet Bochum, 44780 Bochum

Tel  : ++49(0)234-322-5529  E-Mail: woell at pc.ruhr-uni-bochum.de
Fax  : ++49(0)234-3214-182  WWW:    http://www.pc.ruhr-uni-bochum.de

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