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RHF Discrepancy between MRCC and MOLPRO

  • Nike
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8 years 2 months ago #291 by Nike
RHF Discrepancy between MRCC and MOLPRO was created by Nike
Dear Colleagues,

I am getting very different RHF energies in MOLPRO vs stand-alone MRCC, when using the same basis set. It looks like MRCC is finding a local minimum, because the energy is higher than MOLPRO's, and usually this can be fixed by specifying the occupation. However, in both cases the occupation is (10,2):
Code:
# TITLE basis=aug-cc-pVDZ-EMSL calc=CISD mem=8GB core=corr ccmaxit=999 scfmaxit=9999 geom O O 1 r1 O 2 r2 1 theta r1=2.28188 r2=4.5 theta=116.8 unit=bohr
Code:
O:aug-cc-pVDZ-EMSL EMSL BASIS SET LIBRARY 3 0 1 2 4 3 2 10 5 2 11720.0000000 1759.0000000 400.8000000 113.7000000 37.0300000 13.2700000 5.0250000 1.0130000 0.3023000 0.0789600 0.0007100 -0.0001600 0.0000000 0.0000000 0.0054700 -0.0012630 0.0000000 0.0000000 0.0278370 -0.0062670 0.0000000 0.0000000 0.1048000 -0.0257160 0.0000000 0.0000000 0.2830620 -0.0709240 0.0000000 0.0000000 0.4487190 -0.1654110 0.0000000 0.0000000 0.2709520 -0.1169550 0.0000000 0.0000000 0.0154580 0.5573680 0.0000000 0.0000000 -0.0025850 0.5727590 1.0000000 0.0000000 0.0000000 0.0000000 0.0000000 1.0000000 17.7000000 3.8540000 1.0460000 0.2753000 0.0685600 0.0430180 0.0000000 0.0000000 0.2289130 0.0000000 0.0000000 0.5087280 0.0000000 0.0000000 0.4605310 1.0000000 0.0000000 0.0000000 0.0000000 1.0000000 1.1850000 0.3320000 1.0000000 0.0000000 0.0000000 1.0000000

E_RHF,MRCC = -224.2206354441273390
This is the same if I add symm=1.

Code:
*** title memory,8400,m geometry={ O1; O2, O1, r1; O3, O1, r2, O2, theta } r1=2.28188 r2=4.5 theta=116.8 basis={ ! ! OXYGEN (10s,5p,2d) -> [4s,3p,2d] ! OXYGEN (9s,4p,1d) -> [3s,2p,1d] ! OXYGEN (1s,1p,1d) s, O , 11720.0000000, 1759.0000000, 400.8000000, 113.7000000, 37.0300000, 13.2700000, 5.0250000, 1.0130000, 0.3023000, 0.0789600 c, 1.8, 0.0007100, 0.0054700, 0.0278370, 0.1048000, 0.2830620, 0.4487190, 0.2709520, 0.0154580 c, 1.8, -0.0001600, -0.0012630, -0.0062670, -0.0257160, -0.0709240, -0.1654110, -0.1169550, 0.5573680 c, 9.9, 1 c, 10.10, 1 p, O , 17.7000000, 3.8540000, 1.0460000, 0.2753000, 0.0685600 c, 1.3, 0.0430180, 0.2289130, 0.5087280 c, 4.4, 1 c, 5.5, 1 d, O , 1.1850000, 0.3320000 c, 1.1, 1 c, 2.2, 1 } print basis,orbitals {rhf;wf,24,1,0} rcisd

E_RHF,MOLPRO = -224.231538303312

Is there any other reason why MRCC might be giving me a local minimum?

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  • kallay
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8 years 2 months ago #292 by kallay
Replied by kallay on topic RHF Discrepancy between MRCC and MOLPRO
Dear Nike,
If the SCF does not find the global minimum, you should play a bit with the initial guess or the convergence acceleration procedures, because it may resolve the problem. In your case, if I change the initial guess to scfiguess=ao, I get the molpro energy.
Best regards,
Mihaly Kallay

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8 years 2 months ago #293 by Nike
Replied by Nike on topic RHF Discrepancy between MRCC and MOLPRO
Great answer!
Thank you, I will find this useful for many systems in the future.
With best wishes,
Nike Dattani

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