Dear NWChem Developers:
I am trying to do a CCSD(T) optimization on HBr+ using aug-cc-pv5z on H and pp-aug-cc-pv5z on Br. The problem I am having is CCSD iteration does not converge even at 500 steps. The differences in the energy between SCF iteration is actually increasing instead of decreasing. The related output is below,
CCSD iterations
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Iter Residuum Correlation Cpu Wall V2*C2
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1 0.3947204386567 -0.5986246846772 39.4 39.9 14.9
2 0.0777144398021 -0.5668211536264 39.3 39.8 15.0
3 0.1507226170554 -0.5778189847214 39.4 39.9 14.9
4 0.2654166565068 -0.5768900976901 39.5 40.0 15.0
5 0.9146529333630 -0.5776076230098 39.4 40.0 15.1
MICROCYCLE DIIS UPDATE: 5 5
6 0.0442335406897 -0.5726599439331 39.5 40.0 15.0
7 0.0728365126228 -0.5769226318288 39.4 39.9 15.0
8 0.2686042645653 -0.5771582128763 39.4 39.9 15.0
9 0.6598562875828 -0.5774425649866 39.4 39.9 15.0
10 2.8417269601096 -0.5775023587506 39.5 40.0 15.0
MICROCYCLE DIIS UPDATE: 10 5
11 0.0206737603309 -0.5764805831965 39.4 39.9 15.0
12 0.0367361772656 -0.5769149561010 39.3 39.8 15.0
13 0.0858697482857 -0.5773548026063 39.4 39.9 15.0
14 0.2587281370144 -0.5774284785070 39.4 39.9 15.0
... ...
... ...
... ...
The input file for this calculation is,
start name
echo
charge 1
memory stack 4600 mb heap 4100 mb global 14500 mb
geometry noautosym
H -0.17832631 0.97840869 -0.98242772
Br 0.00496505 -0.04724133 -0.02735323
end
BASIS
H library aug-cc-pv5z
Br library aug-cc-pv5z-pp
END
ECP
Br nelec 10
Br ul
2 1.0000000 0.0000000
Br S
2 70.0242570 49.9628340
2 31.1784120 370.0142050
2 7.1565930 10.2414390
Br P
2 46.7734710 99.1122440
2 46.1841200 198.2530460
2 21.7138580 28.2617400
2 20.9417920 56.6233660
Br D
2 50.6988390 -18.6058530
2 50.6447640 -27.9232800
2 15.4475090 -0.3796930
2 15.5002590 -0.7805830
2 2.8003910 0.0359680
2 1.0774800 0.0943970
Br F
2 14.4656060 -1.0912690
2 21.2340650 -2.8876910
END
SCF
DOUBLET
END
tce
FREEZE atomic
thresh 1e-6
maxiter 500
scf
ccsd(t)
end
task tce optimize
I also tried the same calculation with smaller basis (aug-cc-pvqz) and it works fine. Is this a problem related to bad wave functions due to different basis set?
Thanks in advance and best regards,
SR
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