MOLPRO

25 EXCITED STATES WITH EQUATION-OF-MOTION CCSD (EOM-CCSD) 193
***, EOM-CCSD, vector following procedure
memory,2,m
basis=avdz
geometry={h;f,h,r}
r=0.92 Ang
hf;save,2100.2
cis,-4.4,exfile=6000.2
ccsd;save,4000.2
eom,-4.4,checkovlp=1,exfile=6000.2
eompar,inisingl=200,inidoubl=0
ccsd;start,4000.2
eom,2.4,follow=2,exfile=6000.2,checkovlp=1
eompar,inisingl=200,inidoubl=0
eomprint,loce=1
! define basis set
! z-matrix
! define distance
! do SCF calculation, save orbitals
! do CIS calculation, save amplitudes
! do CCSD calculation, save amplitudes
! do EOM-CCSD calculation,
! check overlap of singles with CIS vectors
! stored in record given in exfile
! for first approximation take 200 single CSF
! of approximate hamiltonian
! do CCSD calculation, try to restart
! do EOM-CCSD calculation for state closest
! to 2.4 CIS state, check overlap of singles
! with CIS vectors stored in exfile
! print overlaps of sample and EOM vectors in
! each iteration
http://www.molpro.net/info/current/examples/hf_eom_conv.com
In this example the CIS state 2.4 corresponds to the EOM-CCSD state 1.4!
25.5 Excited states with CIS
Excitation energies can also be calculated using the Configuration-Interaction Singles (CIS)
method. By default, singlet excited states are calculated. Triplet excited states can be obtained
by setting triplet=1 in EOM card. This method cannot be expected to give accurate results,
but can be used for quite large molecules. The states to be computed are specified as in EOM.
Setting trans=1 switches on the calculation of one-electron properties. By default, dipole
moments are calculated. Other required properties can be specified using EXPEC card. Dipole
transition moments are also calculated.
hf
cis,-3.1,1.2,trans=1
25.6 First- and second-order properties for CCSD
First-order and frequency-dependent second-order properties, derived from the expressions based
on the expectation value of a one-electron operator, can be obtained with the CPROP directive
for the closed-shell CCSD method. The methods are described in the following papers:
[1] B. Jeziorski and R. Moszynski, Int. J. Quantum Chem., 48, 161 (1993);
[2] T. Korona and B. Jeziorski, J. Chem. Phys., 125, 184109 (2006);
[3] R. Moszynski, P. S. Żuchowski and B. Jeziorski, Coll. Czech. Chem. Commun., 70, 1109
(2005);
[4] T. Korona, M. Przybytek and B. Jeziorski, Mol. Phys., 104, 2303 (2006).
Note that properties obtained from the expectation-value expression with the coupled cluster
wave function are not equivalent to these derived from gradient or linear-response methods,
although the results obtained with both methods are quite similar.