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Contents 1 General control statements 1.1 .PRINT 2 Definition of the quadratic response function 2.1 .DIPLEN 2.2 .A OPERATOR 2.3 .B OPERATOR 2.4 .C OPERATOR 2.5 .B FREQ 2.6 .C FREQ 2.7 .ALLCMB 3 Excited state properties 3.1 .EXCPRP 4 Control variational parameters 4.1 .SKIPEE 4.2 .SKIPEP 5 Control reduced equations 5.1 .MAXITR 5.2 .MAXRED 5.3 .THRESH 6 Control integral contributions 6.1 .INTFLG 6.2 .CNVINT 6.3 .ITRINT 7 Control trial vectors 7.1 .XQRNRM 8 Advanced/debug flags 8.1 .NOPREC 8.2 .RESFAC 9 References

This section gives directives for the calculation of quadratic response functions ^[1]

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 the specification of one-electron operators for details).

.A OPERATOR

Specification of the A operator (see the specification of one-electron operators for details).

.B OPERATOR

Specification of the B operator (see the specification of one-electron operators for details).

.C OPERATOR

Specification of the C operator (see the specification of 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 transition moments , where i goes from 1 to 5 in each symmetry (four symmetries in this case). The zeros can be substituted for positive integers to generate elements .

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 (see .INTFLG under **HAMILTONIAN).

Default: .INTFLG from **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

References

1. ↑ T. Saue, Post Dirac-Hartree-Fock methods - Properties, in Relativistic Electronic Structure Theory - Part 1: Fundamentals, edited by P. Schwerdtfeger, Elsevier, Amsterdam, 2002.