*QUADRATIC RESPONSE
This section gives directives for the calculation of quadratic response functions [Saue2002a].
General control statements
.PRINT
Print level.
Default:
.PRINT
0
Definition of the quadratic response function
.DIPLEN
Specification of dipole operators for A, B, and C (see One-electron operators for details).
.A OPERATOR
Specification of the A operator (see One-electron operators for details).
.B OPERATOR
Specification of the B operator (see One-electron operators for details).
.C OPERATOR
Specification of the C operator (see One-electron operators for details).
.B FREQ
Specify frequencies of operator B.
Example: 3 different frequencies.
.B FREQ
3
0.001
0.002
0.01
Default: Static case.
.B FREQ
1
0.0
.C FREQ
Specify frequencies of operator C (see .B FREQ).
.ALLCMB
Evaluate all nonzero quadratic response functions and thereby disregarding analysis of overall permutational symmetry.
Default: Evaluate only unique, nonzero, response functions.
Excited state properties
This page describes unreleased functionality. The keywords may not be available in your version of DIRAC.
First order properties of excited states can be computed from the quadratic response function.
.EXCPRP
Give the number of “left” and “right” states in each boson symmetry.
Example:
.EXCPRP
5 5 5 5
0 0 0 0
Compute the excited state expectation values |\langle i|\hat{A}|i\rangle|, where i goes from 1 to 5 in each symmetry (four symmetries in this case). The zeros can be substituted with positive integers to generate transition state moments |\langle i|\hat{A}|j\rangle|.
Control variational parameters
.SKIPEE
Exclude all rotations between occupied positive-energy and virtual positive-energy orbitals.
.SKIPEP
Exclude all rotations between occupied positive-energy and virtual negative-energy orbitals.
Control reduced equations
.MAXITR
Maximum number of iterations.
Default:
.MAXITR
30
.MAXRED
Maximum dimension of matrix in reduced system.
Default:
.MAXRED
100
.THRESH
Threshold for convergence of reduced system.
Default:
.THRESH
1.0D-5
Control integral contributions
The user is encouraged to experiment with these options since they may have an important effect on run time.
.INTFLG
Specify what two-electron integrals to include (default: .INTFLG under **HAMILTONIAN).
.CNVINT
Set threshold for convergence before adding SL and SS integrals to SCF-iterations.
2 (real) Arguments:
.CNVINT
CNVXQR(1) CNVXQR(2)
Default: Very large numbers.
.ITRINT
Set the number of iterations before adding SL and SS integrals to SCF-iterations.
Default:
.ITRINT
1 1
Control trial vectors
.XQRNRM
Normalize trial vectors. Using normalized trial vectors will reduce efficiency of screening.
Default: Use un-normalized vectors.
Advanced/debug flags
.NOPREC
No preconditioning of initial trial vectors.
Default: Preconditioning of trial vectors.
.RESFAC
New trial vector will be generated only for variational parameter classes whose residual has a norm that is larger than a fraction 1/RESFAC of the maximum norm.
Default:
.RESFAC
1000.0