The SURF calculation crashes with an error message like
?ERROR IN VIRTORB: INCORRECT NUMBER OF ORB...
ERROR EXIT
CURRENT STACK: MAIN
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.
Problem:
In parallel calculations (MPPX) the CPU-time of a VSCF
calculation differs considerably from
the real-time (wallclock time).
Solution:
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.
