Excited-state first-order properties: *CCEXGR

In the *CCEXGR section the input that is specific for coupled cluster response calculation of excited-state first-order properties is read in. This section includes presently for example calculation of excited-state dipole moments and second moments of the electronic charge distribution. In many cases the information generated in this way is helpful for making qualitative assignments of the electronic states, for example in conjunction with the oscillator strengths and the orbital analysis of the response eigenvectors presented in the output.

The excited-state properties are available for the models CCS, CC2 and CCSD, but only for singlet states. The theoretical background for the implementation is detailed in Ref.
citeChristiansen:CCLR,Christiansen:QEL. This section has to be used in connection with *CCEXCI for the calculation of excited states.

The properties calculated are in the approach now generally known as coupled cluster response--for these frequency independent properties this coincides with the so-called orbital-unrelaxed energy derivatives (and thus the orbital-unrelaxed finite-field result) for the excited-state total energies as obtained by the sum of the CC ground state energy and the CC response excitation energy.

Note of caution: Default in this section is therefore orbital unrelaxed, while for the ground state first order properties *CCFOP default is relaxed. To find results in a consistent approximation turn orbital relaxation off for the ground state (for CCS, CC2, CCSD) calculation.

.ALLONE

Calculate all of the above-mentioned excited state properties (all the above-mentioned property integrals are needed).

.DIPOLE

Calculate the excited state permanent molecular electric dipole moment (DIPLEN integrals).

.NQCC

Calculate the excited state electric field gradients at the nuclei (EFGCAR integrals).

.OPERAT

READ (LUCMD,'(1X,A8)') LABPROP
Calculate the excited state electronic contribution to the property defined by the operator label LABPROP (corresponding LABPROP integrals needed).

.QUADRU

Calculate the excited state permanent traceless molecular electric quadrupole moment (THETA integrals). Note that the origin is the origin of the coordinate system specified in the MOLECULE.INP file.

.RELCOR

Calculate excited state scalar-relativistic one-electron corrections to the energy (DARWIN and MASSVELO integrals).

.SECMOM

Calculate the excited state electronic second moment of charge (SECMOM integrals).

.SELEXC

READ(LUCMD,*) IXSYM,IXST

Select which excited states the calculation of excited state properties are carried out for. The default is all states according to the CCEXCI input section. When calculating selected states only, provide a list of symmetry and state numbers (order after increasing energy in each symmetry class). This list is read until next input label is found.