[molpro-user] Functions of the new MRCIC program and efficient use of the older MRCI program

[Christian Wiebeler]

Dear Molpro developers and users,

At the moment, I am using Molpro for MRCI calculations and have a couple 
of questions regarding the proper use and efficiency:

1.    Is the MRCIC program still restricted to ground state calculations 
for each given symmetry, i.e. spatial and spin symmetry?


2.    After a MRCI calculation, several energy corrections are printed 
out. The manual and the paper discuss the different Davidson 
corrections, but the Pople corrections are not mentioned. Which 
correction do you recommend for the final excitation energy evaluation?


3.    I managed to run the MRCI calculations with 176 basis functions, 
1232 configurations in reference space and 207 basis functions, 2076 
configurations. However, a calculation with 239 basis functions and 6765 
configurations is constantly crashing with the following error 
message:
“insufficient memory available - require 10572865380 have 
100680817 
the request was for real words” or it just freezes without 
any output for several days. 
I have compute nodes with 40 cores and 256 
GB memory available. How should I choose the optimal conditions for such 
a calculation to finish successfully? Maybe the memory per core is not 
sufficient and I should choose less cores?




Best regards,
Christian