Cubic response calculation of second order moments between excited states and excited state polarizabilities: *CUBIC with .DOUBLE RESIDUE

Calculation of double residues of cubic response functions [169,170,90]. $A,B$,$C$, and $D$-named options refer to the operators in the cubic response function $\langle\!\langle A;B,C,D\rangle\!\rangle_{\omega_b,\omega_c,\omega_d}$. $C$ and $D$ refer to the left hand state and right hand state after the double residue has been taken.

Excited state polarizabilites are only calculated if one or more of the keywords .DIPLEN, .DIPLNX, .DIPLNY, and .DIPLNZ are specified. Only singlet excitations and singlet property operators are implemented.

.APROP, .BPROP

Specify the operators $A$ and $B$, respectively. The line following this option should be the label of the operator as it appears in the file AOPROPER. These two keywords can be repeated for different properties.

.BFREQ

The frequencies $\omega_b$. Input as in .FREQUE. Default only zero frequency (static).

.DIPLEN Sets $A$ and $B$ to dipole operators.

.DIPLNX Sets $A$ and $B$ to the $x$ dipole operator.

.DIPLNY Sets $A$ and $B$ to the $y$ dipole operator.

.DIPLNZ Sets $A$ and $B$ to the $z$ dipole operator.

.DOUBLE REQUIRED. Computes the double residue of the cubic response function. In the case of dipole operators this corresponds to excited state polarizabilities and two-photon transition moments between excited states [171].

.FREQUE
READ *, NFREQ
READ *, FREQ(1:NFREQ)
Sets the frequencies whenever a optical process is specified. Can also be used for the residue calculation and it does then set both $\omega_b$ and $\omega_c$ for the single residue and only $\omega_b$ for the double residue. Default only zero frequency (static).

.MAX IT Maximum number of iterations for solving linear equations, default value is 60.

.MAXITO Maximum number of optimal orbital trial vector microiterations, default value is 5.

.MAXITP Maximum number of iteration for solving eigenvalue equation, default value is 20.

.PRINT Print flag for output, default value is 2. Timer information is printed out if print flag greater than 5. Response vectors printed out if print flag greater than 10.

.ROOTS Number of roots (excited states) to converge for each spatial symmetry.
READ (LUCMD,*) (NTPCNV(J),J=1,NSYM)
Default: one of each symmetry.

.THCLR Threshold for convergence of response vectors, default value is $10^{-3}$.

.THCPP Threshold for convergence of eigenvector, default value is $10^{-3}$.