MOLPRO

47 POTENTIAL ENERGY SURFACES (SURF) 361
ERROR IN VIRTORB: INCORRECT NUMBER OF ORB...
ERROR EXIT
CURRENT STACK:
MAIN
Solution:
• Problem:
Solution:
The program has problems in the symmetry conversion when
restarting a Hartree-Fock calculation from the reference calculation
at the equilibrium geometry. You need to start the
Hartree-Fock calculations independently by using the keywords
start,atden.
In parallel calculations (MPPX) the CPU-time of a VSCF calculation
differs considerably from the real-time (wallclock time).
There may be two reasons for this: (1) Usually a VSCF calculation
spends a significant amount of the total time in the Hartree-
Fock program and the 2-electron integrals program. As the integrals
are stored on disk, 2 processes on the same machine may
write on disk at the same time and thus the calculation time
depends to some extend on the disk controller. It is more efficient
to stripe several disks and to use several controllers. This
problem can be circumvented by distributing the job over several
machines, but limiting the number of processors for each
machine to 1. (2) The integrals program buffers the integrals.
Parallel jobs may require too much memory (factor of 2 plus the
shared memory) and thus the integrals buffering will be inefficient.
Try to reduce the memory as much as you can. It might
be advantageous to separate the memory demanding VCI calculation
from the SURF calculation.