Hello, we would like calculate the RI-MP2 Single-Point energies for systems containing ~400 atoms (~5000 basis functions) on 4-processor Xeon machine with 32GB of RAM with Turbomole 6.0
Starting the single-processor job with less than 16 GB of memory works fine using rimp2 as well as ricc2 module (with option mp2energy only). In the manual is written than the ricc2 algorithm is more efficient than the rimp2 one in dealing with large systems how big of CPU saving using ricc2 algorithm can be expected? What is the difference between these algorithms?
However, we met several problems during the calculations:
Firstly, trying to specify more than 16GB of memory both RIMP2 and RICC2 modules crashed (even for much smaller systems....) with the same message:
" Allocation failure for irreducible tensor analysis !"
Secondly , trying to run parallel ricc2 calculation (while for small system it was working correctly)
the job crashed with the folllowing mesage:
Number of symmetry-nonredundant auxiliary basis functions: 14016
Block lengths for integral files:
frozen occupied (BOI): 26 Mbyte
active occupied (BJI): 70 Mbyte
active virtual (BAI): 300 Mbyte
frozen virtual (BGI): 0 Mbyte
general (BTI): 395 Mbyte
=========================================================================
========================
internal module stack:
------------------------
ricc2
ccmkbaoi
========================
Unknown error in cc_bmpiresort
ricc2 ended abnormally
ricc2 ended abnormally
MPI Application rank 0 exited before MPI_Finalize() with status 13
forrtl: error (78): process killed (SIGTERM)
What would be more efficient - to run the job on 4 proccessors (each with 8 GB memory) , or 2x16Gb or 1x32GB?
And the last quenstion: can be the maximum size of scratch disk space specified during the ricc2 procedure? I found in the manual how to handle it only in scf and mp2 jobs....
Thank you very much for your help!
Martin