In the following test input, the ^1Sigma^+ and ^1Pi excited states of the HF molecule are calculated by the CC(2)-LRT method.
Code: Select all
ATOMBASIS
HF
test
Atomtypes=2 Angstrom
Charge=1.0 Atoms=1 Basis=3-21G
H 0.0000000000 0.0000000000 0.0000000000
Charge=9.0 Atoms=1 Basis=3-21G
F 0.0000000000 0.0000000000 0.9500000000
**DALTON INPUT
.RUN WAVE FUNCTIONS
**WAVE FUNCTIONS
.CC
*CC INPUT
.CC(2)
*CCEXCI
.NCCEXC
1 1 1 0
**END OF DALTON INPUT
^1A1 16.91703 eV
^1B1 11.27095 eV
^1B2 11.27095 eV
but the CC(2)-LRT results are strange:
^1A1 26.98359 eV
^1B1 3.13472 eV
^1B2 10.48748 eV
But if only one excited state is specified after .NCCEXC, reasonable CC(2)-LRT results can be obtained:
^1A1 16.36293 eV
^1B1 10.48748 eV
^1B2 10.48748 eV
This problem was not found for CCS, CC2, CCSD, CC3, and CCSDR(3) with LRT calculations. The 2015.1 Version of Dalton was used. Maybe it has been solved in the 2016 version? Thanks!