From NWChem
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Just Got Here
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| 1:30:15 AM PST - Sat, Mar 3rd 2012 |
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Dear all,
I need to ab intio calculations with where no. of basis functions ~ 1000 at MP2 l.o. theory with basis sets such as aug-cc-pvtz.
My hardware is a beowulf cluster with 7x intel i7 @ 3.40GHz machines with 16gb memory each.
Nwchem is compiled with openmpi. The jobs run fine in parallel, and with ~500-600 basis fns the performance is good. But with larger systems, the scf takes too long. Both direct and semidirect.
The disk I/O is very slow so i need to to direct scf calculationsfor the integral computation or semidirect with very limited disk I/O.
But direct seems very expensive
f.e. water cluster of 11 units takes 2hrs for a S.P.E. at MP2/aug-cc-pvtz on the given hardware. Of this the SCF takes 45 mins!
1. Is the time reasonable?
2. Are there some optimal values for stack, heap and global memory (other than default to maximize chacing)?
Thanks in advance!
Jonathan
Some relevant info :
The scf options were :
scf
semidirect filesize 10000000
end
mp2
freeze atomic
end
task mp2
Memory information
------------------
heap = 129602401 doubles = 988.8 Mbytes
stack = 129602401 doubles = 988.8 Mbytes
global = 259204800 doubles = 1977.6 Mbytes (distinct from heap & stack)
total = 518409602 doubles = 3955.2 Mbytes
verify = yes
hardfail = no
Superposition of Atomic Density Guess
-------------------------------------
Sum of atomic energies: -833.58996280
Integral file = ./scr/test.aoints.00
Record size in doubles = 65536 No. of integs per rec = 32766
Max. records in memory = 0 Max. records in file = 2478
No. of bits per label = 16 No. of bits per value = 64
#quartets = 9.885D+08 #integrals = 3.954D+10 #direct = 94.2% #cached = 5.8%
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