MOLPRO

25 EXCITED STATES WITH EQUATION-OF-MOTION CCSD (EOM-CCSD) 194
For the first-order properties the one-electron operators should be specified in the EXPEC card,
while for the second-order properties – in the POLARI card. A density can be saved by specifying
the DM card.
For the first-order properties the option XDEN=1 should be always given. Other options specify
a type of the one-electron density, which can be either the density directly derived from the
expectation-value expression, see Eq. (8) of Paper 2, or the modified formula, rigorously correct
through the O(W 3 ) Møller-Plesser (MP) order, denoted as ¯X(3) resp in Papers 1 and 2. In the
first case the option PROP ORDER=n can be used to specify the approximation level for single
and double excitation parts of the so-called S operator (see [2], Eq. (9)); n = ±2,±3,±4, where
for a positive n: all approximations to S up to n are used, and for a negative n only a density
with S obtained on the |n| level will be calculated. Another option related to the S operator is
HIGHW=n, where n = 0,1; if n=0, some parts of S 1 and S 2 operators of a high MP order are
neglected. Below an example of a standard use of this density is given:
CPROP,XDEN=1,PROP ORDER=-4,HIGHW=1
In the second case the options X3RESP=1 and the CPHF,1 card (or alternatively the EXPEC
card) should be specified,
CPROP,XDEN=1,X3RESP=1;CPHF,1
For the second-order properties always the following options should be given:
CPROP,PROPAGATOR=1,EOMPROP=1
The recommended CCSD(3) model from Paper 4 requires that additionally the PROP ORDER=3
and HIGHW=0 options are specified. Frequencies for dynamic properties (in atomic units)
should be given in variables OMEGA RE (real parts) and OMEGA IM (imaginary parts). If one
of these arrays is not given, it is filled with zeros. Other options for the second-order properties
involve
OMEGAG
DISPCOEF=n
THRPROPAG
STARTT1=n
(default 0.3). There are two linear-equation solvers, OMEGAG is a
minimum frequency, for which the second solver (working for large
frequencies) is used.
if n > 0, calculate dispersion integrals for the van der Waals coefficients
with operators given in the POLARI card, using n as a number
of frequencies for the numerical integration. In this case the frequency
values given in OMEGA RE and OMEGA IM are ignored. If
two molecules are calculated in the same script one after another, also
the mixed dispersion integrals are calculated. The isotropic C 6 coefficient
is stored in a variable DISPC6. All necessary informations
for the calculation of dispersion integrals are written to the ascii file
name.dispinfo, where name is the name of the MOLPRO script.
if given, use this threshold as a convergence criterion for the linearequation
solver for the first-order perturbed CCSD amplitudes.
various start options for the iterative linear-equation solver for the
first-order perturbed CCSD amplitudes, the most useful is n = 0 (zero
start) and n = 7 (start from the negative of the r.h.s. vector rescaled by
some energetic factors dependent on the diagonal of the Fock matrix
and the specified frequency).