I am looking at the conversion of chorismate to prephenate in Chorismate Mutase, to benchmark a hacky EFMO-RHF:MP2 method we've implemented in our group. Casper Steinmann did an adiabatic mapping of the reaction path, and we though it'd be cool to do coupled cluster single point energies on snapshots from the reaction path and some something ONIOM style.
Figure 1: Snapshot 1 from the reaction path; chorismate to prephanate
Anyways, the reaction complex contains 118 electrons, so we fired up MOLPRO2012 and started looking at the DF-LCCSD(T0)-F12a method. A name you should probably memorize from now on.
The single point energy evaluation took 3:43 hours with the VDZ-F12 basis set! Mind you, this was on only a single CPU core with 4 GB 16GB of RAM allocated, so no supercomputers were involved.
First I though the calculation had crashed because it didn't show up in the queue. My first attempt with the 3-21G basis set didn't converge because I failed to set the charge to -2, but this time around Molpro actually gave me an energy!
Next problem on my list is to calculate the good old MP2/cc-pVTZ energy I need to subtract in order to get my ONIOM results. Those are going to take about 5-10 hours on 8 cores.
Next problem on my list is to calculate the good old MP2/cc-pVTZ energy I need to subtract in order to get my ONIOM results. Those are going to take about 5-10 hours on 8 cores.
This is what the input file looked like for anyone interested
memory,2000,M
geomtyp=xyz
geometry
24
NS= 27 NA= 105 NF= 9 EFMO2-RHF:MP2 (this line is just a title btw)
C 42.243912717439 56.985332654358 33.508219032291
O 44.083656765173 58.469818126062 33.547456767374
C 42.170657938422 56.969234127412 32.053802633762
O 43.705108088223 57.205919113255 35.368497584787
C 41.129420410826 56.416380137206 31.405612518418
O 36.855437867615 57.552564896356 32.240095659821
C 40.011578869479 55.731334232825 32.133332774369
O 37.952282803211 59.164070642440 31.158486994867
C 39.926225853593 56.110094283828 33.626395940165
O 40.227454849874 54.351343596304 31.951217705746
C 41.196604656028 56.578036178752 34.246569733982
O 38.910804760126 57.082428023235 33.866893577924
C 38.968148927395 58.213925767965 33.092045796028
C 39.831866096203 59.221137407117 33.269727518172
C 43.428858040104 57.602185825538 34.190487998445
C 37.845543926101 58.319486314173 32.113613710711
H 39.478451838017 53.847769952241 32.300919500400
H 39.060609728200 56.030078213449 31.676260590468
H 39.584331039092 55.233181854460 34.161137739114
H 41.108061134298 56.387696261961 30.326013340305
H 42.988978401897 57.425894863516 31.511012407792
H 41.233442365036 56.630502649395 35.323808064193
H 40.574407364526 59.218144574703 34.050005215454
H 39.764972282572 60.084246967681 32.627123054496
end
set,charge=-2
set,spin=0
basis={
C=vdz-f12
H=vdz-f12
O=vdz-f12
}
DF-HF,DF_BASIS=vdz-f12
DF-LCCSD(T)-F12,DF_BASIS=vdz-f12
Further reading:
Molpro manual entry: http://www.molpro.net/info/2012.1/doc/update/node10.html