Dear all,
A computation of benzene excitations with creom(t)ac with this input:
MEMORY total 48000 mb stack 2000 mb heap 2000 mb
START tce_benzene_MeOH_eomcc
GEOMETRY UNITS ANGSTROM
C 0.759749176 1.031275058 0.373772394
H 1.435016257 1.875664269 0.374704616
C 1.266617787 -0.267362341 0.421273076
H 2.334915967 -0.429180190 0.459432338
C 0.395320544 -1.355991164 0.424905109
H 0.788661934 -2.362492586 0.463035490
C -0.982205637 -1.146654408 0.381270236
H -1.657656316 -1.991140192 0.385121003
C -1.489346115 0.151149791 0.337572337
H -2.557947039 0.313750489 0.307719001
C -0.618775155 1.240331207 0.333883729
H -1.011761615 2.247106897 0.304369215
END
BASIS spherical
* library maug-cc-pVTZ
END
SCF
SINGLET
RHF
END
TCE
creom(t)ac
emin_act -1.0
emax_act 1.0
2eorb
2emet 13
split 8
TILESIZE 15
FREEZE CORE ATOMIC
NROOTS 2
TARGET 1
IO GA
END
TASK TCE ENERGY
set tce:thresheom 1.0d-4
produces negative excitation energies:
CR-EOMCCSD(T)-ACT(II) total energy / hartree = -231.241750851019901
CR-EOMCCSD(T)-ACT(II) excitation energy (eV) = -2.39452
corresponding excitation energy = 0
corresponding excitation energy = 0
corresponding excitation energy = 0
corresponding excitation energy = 0
CR-EOMCCSD(T)-act Intermediates cpu wall time 61.9 67.3
cr_N i1_1 nr of boxes 152
cr_N i1_2 nr of boxes 4150
creom_N i2_1 nr of boxes 152
creom_N i2_2 nr of boxes 4150
creom_N i2_3 nr of boxes 152
creom_N i2_4 nr of boxes 4150
CR-EOMCCSD(T)-ACT(II) triples loop cpu wall 1528.3 1527.3
CR-EOMCCSD(T)-ACT(II) total energy / hartree = -231.244410865723324
Now, I might be choosing a wrong active space, but already the end of EOM-CCSD is wrong. 2 last iterations read:
Iteration 65
0.0000001659096 -0.0000000016228 -0.00000 13.6 13.7
0.0000000133072 0.0000000000255 0.00000 13.6 13.7
Iteration 66
0.0000000920125 -0.0000000006372 -0.00000 13.8 13.9
0.0000000078340 0.0000000000164 0.00000 13.8 13.9
while if I change the window of active space to [-0.5,1.0] not only I obtain reasonable energies with CR-EOMCCSD(T)-ACT:
CR-EOMCCSD(T)-ACT(II) triples loop cpu wall 232.6 233.0
CR-EOMCCSD(T)-ACT(II) total energy / hartree = -230.652869292841928
CR-EOMCCSD(T)-ACT(II) excitation energy (eV) = 5.81811
CR-EOMCCSD(T)-act Intermediates cpu wall time 83.5 86.6
cr_N i1_1 nr of boxes 152
cr_N i1_2 nr of boxes 4150
creom_N i2_1 nr of boxes 152
creom_N i2_2 nr of boxes 4150
creom_N i2_3 nr of boxes 152
creom_N i2_4 nr of boxes 4150
CR-EOMCCSD(T)-ACT(II) triples loop cpu wall 232.6 232.5
CR-EOMCCSD(T)-ACT(II) total energy / hartree = -230.623758973731810
CR-EOMCCSD(T)-ACT(II) excitation energy (eV) = 6.61024
but also EOMCCSD converges to non-zero values:
Iteration 38
0.0000000000437 0.2234464413987 6.08029 20.8 20.9
0.0000001117331 0.2495576796759 6.79081 20.8 20.9
Iteration 39
0.0000000000813 0.2234464413984 6.08029 20.8 20.9
0.0000000675230 0.2495576799136 6.79081 20.8 20.9
Shouldn't at least EOM-CCSD give me the same answer (unless it's not really EOM-CCSD)?
Best,
Ewa Pastorczak
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