Linear response excitation energies calculation: *LINEAR with .SINGLE RESIDUE

Single residues of the linear response function is computed. Residues of a linear response function correspond to transition moments and the associated poles correspond to vertical electronic excitation energies.

In the same RESPONSE CALCULATION THESE EXCITATION PROPERTIES CAN BE CALCULATED TOGETHER WITH LINEAR RESPONSE PROPERTIES AND WITH LONG RANGE DISPERSION COEFFICIENTS, BUT NOT TOGETHER WITH QUADRATIC OR CUBIC RESPONSE.

REQUIRED KEYWORDS:

.SINGLE RESIDUE REQUIRED TO GET EXCITATION ENERGIES, WITHOUT THIS KEYWORD THE LINEAR RESPONSE FUNCTION WILL BE EVALUATED, SEE SEC. .

OPTIONAL KEYWORDS

.ABCHK SETS UP #MATH1178# AND #MATH1179# USED IN SOLVING THE SINGLE RESIDUE LINEAR RESPONSE EQUATION. ONLY FOR DEBUGGING PURPOSES.

.ABSYM TESTS THE SYMMETRY OF #MATH1180# AND #MATH1181# IN THE REDUCED SPACE. ONLY FOR DEBUGGING PURPOSES.

.ANTTES TEST THE ANTISYMMETRY OF THE SINGLE RESIDUE RESPONSE VECTOR. ONLY FOR DEBUGGING PURPOSES.

.DIPLEN SETS AND TO DIPOLE OPERATORS.

.DIPLNX/Y/Z SETS AND TO THE X, Y, OR Z COMPONENT OF THE DIPOLE LENGTH OPERATORS, RESPECTIVELY.

.DIPMAG SETS AND TO ANGULAR MOMENTUM OPERATORS.

.DIPMGX/Y/Z SETS AND TO THE X, Y, OR Z COMPONENT OF THE ANGULAR MOMENTUM OPERATORS.

.DIPVEL SETS AND TO THE DIPOLE VELOCITY OPERATORS.

.DIPVLX/Y/Z SETS AND TO THE X, Y, OR Z COMPONENT OF THE DIPOLE VELOCITY OPERATOR, RESPECTIVELY.

.MAX IT
READ *, MAXITP
MAXIMUM NUMBER OF ITERATIONS FOR SOLVING THE SINGLE RESIDUE LINEAR RESPONSE EIGENVALUE EQUATION. DEFAULT IS 60.

.MAXITO
READ *, MAXITO
MAXIMUM NUMBER OF ITERATIONS IN THE OPTIMAL ORBITAL ALGORITHM [21]. DEFAULT IS 5.

.NSTART
READ (LUCMD,*) (NPPSTV(J),J=1,NSYM)
THE NUMBER OF START VECTORS TO BE USED IN THE OPTIMIZATION OF THE TRANSITION VECTORS IN EACH SYMMETRY. BY DEFAULT THIS IS SET EQUAL TO THE NUMBER OF EXCITED STATES THAT HAVE BEEN REQUESTED THROUGH THE KEYWORD .ROOTS. IT CAN BE RELEVANT TO MAKE THE NUMBER OF START VECTORS BIGGER, FOR EXAMPLE IF THE MOLECULE HAS HIGHER SYMMETRY THAN USED IN THE CALCULATION. IN THIS CASE ONE MIGHT NEED MORE START VECTORS TO GET A REPRESENTATIVE OF EACH SYMMETRY.

.NSIMUL
READ (LUCMD,*) (NPPSIM(J),J=1,NSYM)
THE NUMBER OF EIGENVECTORS TO SOLVE SIMULTANEOUSLY IN EACH SYMMETRY. NORMALLY DECIDED AUTOMATICALLY BY THE PROGRAM DEPENDING ON AVAILABLE MEMORY AND SIZE OF EIGENVECTORS.

.PRINT
READ *,IPRPP
SETS PRINT LEVEL FOR SINGLE RESIDUE LINEAR RESPONSE MODULE. DEFAULT IS 2.

.PROPRT
READ '(A)', LABEL
CALCULATE EITHER SINGLET OR TRIPLET TRANSITION MOMENTS FOR A GIVEN OPERATOR WITH LABEL; LABEL. (THE CALCULATION OF THE OPERATOR MUST BE SPECIFIED TO THE INTEGRAL MODULE, SEE SECTION .) THIS KEYWORD MAY BE REPEATED FOR DIFFERENT PROPERTIES.

.QUADMOM SETS AND TO THE QUADRUPOLE OPERATORS.

.QUADXX/XY/XZ/YY/YZ/ZZ SETS AND TO THE XX, XY, XZ, YY, YZ, OR ZZ COMPONENT OF THE QUADRUPOLE OPERATOR, RESPECTIVELY.

.RESTPP RESTART OF SINGLE RESIDUE RESPONSE CALCULATION. THIS CAN ONLY BE USED IF THE ROOT WHICH IS SPECIFIED IS THE SAME WHICH WAS USED LAST IN THE PREVIOUS SINGLE RESIDUE RESPONSE CALCULATION.

.ROOTS
READ '*',(ROOTS(I) I=1,NSYM)
NUMBER OF ROOTS. THE LINE FOLLOWING THIS OPTION CONTAINS THE NUMBER OF EXCITED STATES PER SYMMETRY. EXCITATION ENERGIES ARE CALCULATED FOR EACH STATE AND IF ANY OPERATORS ARE GIVEN, SYMMETRY-ALLOWED TRANSITION MOMENTS ARE CALCULATED BETWEEN THE REFERENCE STATE AND THE EXCITED STATES. REMEMBER TO INCREASE .MAXRM IF MANY ROOTS ARE SPECIFIED. DEFAULT: ONE OF EACH SYMMETRY.

.SPIN-O SETS AND TO SPIN-ORBIT OPERATORS. WARNING: THIS OPTION IMPLIES .TRIPLET AND FORCES THE EXCITATIONS TO BE OF TRIPLET SYMMETRY, AND ALL OPERATORS--INCLUDING E.G. .DIPLEN--WILL BE ASSUMED BY THE PROGRAM TO BE OF TRIPLET SYMMETRY!!

.SPNORX/Y/Z SETS AND TO THE X, Y, OR Z COMPONENT OF THE SPIN-ORBIT OPERATOR, RESPECTIVELY. WARNING: THIS OPTION IMPLIES .TRIPLET AND FORCES THE EXCITATIONS TO BE OF TRIPLET SYMMETRY, AND ALL OPERATORS--INCLUDING E.G. .DIPLEN--WILL BE ASSUMED BY THE PROGRAM TO BE OF TRIPLET SYMMETRY!!

.THCPP
READ *, THCPP
THRESHOLD FOR SOLVING THE SINGLE RESIDUE LINEAR RESPONSE EIGENVALUE EQUATION. DEFAULT IS 1.0D-3; NOTE THAT THIS NUMBER SHOULD BE AT LEAST 10 TIMES BIGGER THAN THE FINAL GRADIENT NORM IN THE SCF/MCSCF WAVE FUNCTION OPTIMIZATION, OTHERWISE YOU MAY ENCOUNTER NUMERICAL PROBLEMS. THE ACCURACY OF THE POLE (EXCITATION ENERGY) WILL BE QUADRATIC IN THIS THRESHOLD, THUS THE DEFAULT CORRESPONDS TO APPROXIMATELY 6 DIGITS. THE ACCURACY OF TRANSITION MOMENTS WILL BE LINEAR IN THIS THRESHOLD.

.TRIPLET CALCULATE TRIPLET EXCITATION ENERGIES AND TRANSITION MOMENTS. WILL ALSO MAKE A SIMULTANEOUS LINEAR RESPONSE CALCULATION OF TRIPLET SYMMETRY.

.OLSEN CI TRIAL VECTORS ARE OBTAINED WITH OLSEN ALGORITHM.