[molpro-user] surprisingly slow mp2 gradient calculations with molpro

[Toon Verstraelen]

Dear Molpro users,

We are currently testing a compilation of molpro on our ibm p575
machines (AIX 5.3). Most calculations run fine but when we try to run an 
mp2 gradient calculation, molpro keeps running without further output 
after the mp2 energy is reported in the output file. This is the input 
file. It is just a test job, molpro.in

punch,molpro.pun,rewind
geomtyp=xyz
geometry={
include,geometry.xyz
}
basis,STO-3G
SET,symmetry=0
hf
basis,6-311++G**
SET,symmetry=0
hf
mp2
force
pop


this is geometry.xyz

    30

  H     3.559515    -3.602968     0.480477
  H     0.000000     0.000000     0.000000
  H     2.231618    -0.126968    -2.973653
  H     2.164509    -5.199926    -2.981076
  H    -1.525048    -1.769387    -2.541999
  H    -0.283606    -4.942521    -0.158983
  O     3.211113    -4.202985    -0.172099
  O     1.622107    -5.196719    -2.205522
  O     0.578705    -4.569284     0.135543
  O     1.634017    -2.537234    -1.790187
  O    -0.170479    -0.889723    -0.455256
  O     1.332520    -0.013415    -2.763644
  O    -0.707978    -1.494727    -2.920517
Si     1.754767    -3.998427    -0.991862
Si     0.592276    -1.284170    -1.911350
  H     3.097785    -1.009335     6.285552
  H     0.000000     0.000000     1.682236
  H     2.076392     0.668372     5.305142
  H     3.170994    -3.996060     3.617948
  H     3.143732     0.626618     2.427053
  H     1.640463    -4.632139     6.450378
  O     3.293025    -1.899958     6.099096
  O     2.990040    -4.078557     4.551136
  O     1.253281    -3.746910     6.474897
  O     1.340477    -2.068433     4.077228
  O    -0.065984    -0.094797     2.623509
  O     2.188434     0.431384     4.374149
  O     2.529447    -0.016530     2.124618
Si     2.135106    -2.835983     5.351803
Si     1.429452    -0.586945     3.296122


With another very famous quantum chemistry package this job runs for 70 
minutes while molpro was still running after 48 hours on the same 
machine, although the HF and mp2 energy part in molpro is fast. We had 
the chance the run the same job with molpro on yet a larger cluster, 
where it took 30 hours to complete the molpro job, which is extremely 
long compared to the 70 minutes. We believe that this must be a bug in 
molpro or an unpractical default setting that causes the long run time. 
Are there other users that experience similar problems? Is there a 
work-around?


    15

  H    -0.059728    -0.411120    -0.618055
  H     0.514182    -3.191541     3.083949
  H    -3.101425    -2.004277     4.342903
  H     1.902183    -0.100208     2.828450
  H    -2.666575    -4.089570     1.406482
  H    -0.884653     1.977845     1.925963
  O     0.215520     0.237492     0.010073
  O     1.373611    -0.721015     2.351302
  O    -0.387441     1.342727     2.416665
  O    -1.240360    -1.242104     1.727592
  O    -0.323932    -3.579847     2.881498
  O    -2.167500    -1.994261     4.202866
  O    -2.905062    -3.375850     1.976998
Si    -0.036196    -0.116254     1.642964
Si    -1.630889    -2.527372     2.695378


I have also tried direct-mp2 and different basis sets (6-31++g** and 
cc-pVDZ), but the symptoms are exactly the same.


best regards,

Toon Verstraelen