MOLPRO

20 THE CI PROGRAM 157
20.3.12 Starting wavefunction
START,readc1,irest;
readc1:
irest:
record name from which the wavefunction is restored for a
restart. In the case of coupled cluster methods (CCSD, QCISD,
BCCD), the amplitudes are read from record readc1 and used
for restart (presently only implemented for closed-shell methods)
If nonzero, the CI coefficients are read and used for the restart;
otherwise, only the wavefunction definition is read in.
20.3.13 One electron properties
EXPEC,oper 1 ,oper 2 ,oper 3 ,. . . ;
After the wavefunction determination, calculate expectation values for one-electron operators
oper i . See section 6.13 for the available operators and their keywords. In multi-state calculations
or in projected calculations, also the transition matrix elements are calculated.
20.3.14 Transition moment calculations
TRANS,readc1,readc2,[BIORTH],[oper 1 ,oper 2 ,oper 3 ,. . . ];
Instead of performing an energy calculation, only calculate transition matrix elements between
wavefunctions saved on records readc1 and readc2. See section 6.13 for a list of available
operators and their corresponding keywords. If no operator names are specified, the dipole
transition moments are calculated.
If option BIORTH is given, the two wavefunctions may use different orbitals. However, the
number of active and inactive orbitals must be the same in each case. Note that BIORTH is not
working for spin-orbit matrix elements. Under certain conditions it may happen that biorthogonalization
is not possible, and then an error message will be printed.
20.3.15 Saving the density matrix
DM,record.ifil,[idip];
The first order density matrices for all computed states are stored in record record on file ifil.
If idip is not zero, the dipole moments are printed starting at iteration idip. See also NATORB.
In case of transition moment calculation, the transition densities are also stored, provided both
states involved have the same symmetry.
20.3.16 Natural orbitals
NATORB,[RECORD=]record.ifil,[PRINT=nprint],[CORE[=natcor]];
Calculate natural orbitals. The number of printed external orbitals in any given symmetry is
nprint) (default 2). nprint=-1 suppressed the printing. If record is nonzero, the natural orbitals
and density matrices for all states are saved in a dump record record on file ifil. If record.ifil is
specified on a DM card (see above), this record is used. If different records are specified on the