MOLPRO

42 GEOMETRY OPTIMIZATION (OPTG) 318
These variables are set automatically by the CI and/or CCSD programs. It is the user’s responsibility
to use the correct variable name; an error exit occurs if the specified variable has not been
defined by the last program or the user.
Note: The use of the VARIABLE option triggers NUMERICAL, so optimization can be very
inefficient!
42.2.18 Printing options (PRINT)
PRINT,code=level,. . . ;
Enables printing options. Usually level should be omitted or 0; values of level > 0 produce
output useful only for debugging. code can be
HESSIAN
HISTORY
GRADIENT
OPT
prints the updated hessian matrix. Note that its diagonal elements are
printed anyway.
prints the complete set of previous geometries, gradients and energies.
prints extended gradient information
prints detailed information about the optimization process (mainly for
debugging).
Several print options can be specified with one PRINT command.
42.2.19 Conical Intersection optimization (CONICAL)
To optimize a conical intersection between two electronic states having the same spin, three
vectors must be evaluated at SA-CPMCSCF level:
1) Non-Adiabatic Derivative Coupling (DC).
2) Gradient of the lower state (LSG).
3) Gradient of the upper state (USG).
This requires three different CPMCSCF directives in the MULTI input:
CPMCSCF, NACM, S i , S j , ACCU=1.0d-7, record=record1.file
CPMCSCF, GRAD, S i , SPIN=Spin of state S i , ACCU=1.0d-7, record=record2.file
CPMCSCF, GRAD, S j , SPIN=Spin of state S j , ACCU=1.0d-7, record=record3.file
where S i ,S j are the electronic states in the usual format istate.istsym, and record[n].file specifies
the name and the file number where CPMCSCF solutions should be stored. Parameter SPIN is
half of the value in the WF card used to define the electronic state.
Things to remember:
i) Specify always three different record.file on the CPMCSCF directives.
ii) Evaluate the CPMCSCF for USG always last.
iii) Skip the DC evaluation if the conical intersection involves states with different spin (e.g.,
a Singlet/Triplet crossing) because the coupling is then zero.