*ORBITAL INPUT

Purpose:

To define an initial set of molecular orbitals and to control the use of super symmetry, frozen orbitals, deletion of orbitals, reordering and punching of orbitals.

.5D7F9G

Delete unwanted components in Cartesian d, f, and g orbitals. (s in d; p in f; s and d in g). By default, HERMITATOMIC INTEGRALS IN SPHERICAL BASIS, AND THIS OPTION SHOULD THEREFORE NOT BE NEEDED.

.AO DELETE

READ (LUINP,*) THROVL
DELETE MO'S BASED ON CANONICAL ORTHONORMALIZATION USING EIGENVALUES AND EIGENVECTORS OF THE AO OVERLAP MATRIX.
THROVL: LIMIT FOR BASIS SET NUMERICAL LINEAR DEPENDENCE (EIGENVECTORS WITH EIGENVALUE LESS THAN THROVL ARE EXCLUDED). DEFAULT IS 1.010.

.CMOMAX

READ (LUINP,*) CMAXMO
ABORT CALCULATION IF THE ABSOLUTE VALUE OF ANY INITIAL MO COEFFICIENT IS GREATER THAN CMAXMO (DEFAULT : CMAXMO = ). LARGE MO COEFFICIENTS CAN CAUSE SIGNIFICANT LOSS OF ACCURACY IN THE TWO-ELECTRON INTEGRAL TRANSFORMATION.

.DELETE

READ (LUINP,*) (NDEL(I),I = 1,NSYM)
DELETE ORBITALS, I.E. NUMBER OF MOLECULAR ORBITALS IN SYMMETRY "I" IS NUMBER OF BASIS FUNCTIONS IN SYMMETRY "I" MINUS "NDEL(I)".
ONLY FOR USE WITH ".MOSTART" OPTIONS "FORM12" OR "FORM18", IT CANNOT BE USED WITH "H1DIAG", "EWMO", OR "HUCKEL", AND THE OTHER RESTART OPTIONS AS "NEWORB" READS THIS INFORMATION FROM FILE AND THIS WILL OVERWRITE WHAT EVER WAS SPECIFIED HERE.

.FREEZE

DEFAULT: NO FROZEN ORBITALS.

VERBATIM565#

WHERE INOROT = ORBITAL NUMBERS OF THE ORBITALS TO BE FROZEN (NOT ROTATED) IN SYMMETRY "ISYM" BOTH IN SCF AND MCSCF AFTER ANY REORDERING (COUNTING FROM 1 IN EACH SYMMETRY).
MUST BE SPECIFIED AFTER ALL OPTIONS REDUCING THE NUMBER OF ORBITALS. FROZEN OCCUPIED ORBITALS IN SCF CAN ONLY BE SPECIFIED IN THE *SCF INPUT INPUT MODULE AND FROZEN INACTIVE ORBITALS IN MCSCF CAN ONLY BE SPECIFIED IN THE *OPTIMIZATION INPUT MODULE.

.GRAM-SCHMIDT ORTHONORMALIZATION

DEFAULT.
GRAM-SCHMIDT ORTHONORMALIZATION OF INPUT ORBITALS.

.LOCALIZATION

READ (LUINP,*) REWORD
SPECIFY THAT THE DOUBLY OCCUPIED (INACTIVE) ORBITALS SHOULD BE LOCALIZED AFTER SCF OR MCSCF IS CONVERGED. ONE OPTION FOR LOCALIZATION OF THE ORBITALS IS CURRENTLY AVAILABLE:

BOYLOC/TT>

USE THE BOYS LOCALIZATION SCHEME [].

.MOSTART

MOLECULAR ORBITAL INPUT
READ (LUINP,'(1X,A6)') RWORD
WHERE RWORD IS ONE OF THE FOLLOWING:

FORM12/TT>

FORMATTED INPUT (6F12.8) SUPPLIED AFTER **MOLORB OR **NATORB KEYWORD. USE ALSO ".DELETE" IF ORBITALS WERE DELETED.

FORM18/TT>

FORMATTED INPUT (4F18.14) SUPPLIED AFTER **MOLORB OR **NATORB KEYWORD. USE ALSO ".DELETE" IF ORBITALS WERE DELETED.

EWMO/TT>

START ORBITALS GENERATED BY PROJECTING THE EWMO HÜCKEL EIGENVECTORS IN A GOOD GENERALLY CONTRACTED ANO BASIS SET ONTO THE PRESENT BASIS SET. THE EWMO MODEL GENERALLY WORKS BETTER THAN THE EHT MODEL. DEFAULT INITAL GUESS FOR MOLECULES IN WHICH ALL ATOMS HAVE A NUCLEAR CHARGE LESS THAN OR EQUAL TO 36. NOTE: EWMO/HUCKEL IS NOT IMPLEMENTED YET IF ANY ELEMENT HAS A CHARGE LARGER THAN 36). THE START DENSITY WILL THUS BE CLOSE TO ONE GENERATED FROM ATOMIC DENSITIES, BUT WITH MOLECULAR VALENCE INTERACTION IN THE EWMO MODEL. THIS WORKS A LOT BETTER THAN USING A MINIMAL BASIS SET FOR EMWO.

HUCKEL/TT>

START ORBITALS GENERATED BY PROJECTING THE EHT HÜCKEL EIGENVECTORS IN A GOOD GENERALLY CONTRACTED ANO BASIS SET ONTO THE PRESENT BASIS SET. NOTE: EWMO/HUCKEL IS NOT IMPLEMENTED YET IF ANY ELEMENT HAS A CHARGE LARGER THAN 36. THE START DENSITY WILL THUS BE CLOSE TO ONE GENERATED FROM ATOMIC DENSITIES, BUT WITH MOLECULAR VALENCE INTERACTION IN THE HÜCKEL MODEL. THIS WORKS A LOT BETTER THAN USING A MINIMAL BASIS SET FOR HÜCKEL.

H1DIAG/TT>

START ORBITALS THAT DIAGONALIZE ONE-ELECTRON HAMILTONIAN MATRIX (DEFAULT FOR MOLECULES CONTAINING ELEMENTS WITH A NUCLEAR LARGER THAN 36).

NEWORB/TT>

INPUT FROM SIRIUS RESTART FILE (SIRIUS.RST FILE) WITH LABEL "NEWORB "

OLDORB/TT>

INPUT FROM SIRIUS RESTART FILE (SIRIUS.RST FILE) WITH LABEL "OLDORB "

SIRIFC/TT>

INPUT FROM SIRIUS INTERFACE FILE ("SIRIFC")

.PUNCHINPUTORBITALS

PUNCH INPUT ORBITALS WITH LABEL **MOLORB, FORMAT (4F18.14). THESE ORBITALS MAY E.G. BE TRANSFERRED TO ANOTHER COMPUTER AND READ THERE WITH ".MOSTART" FOLLOWED BY " FORM18" ON NEXT LINE FROM THIS INPUT SECTION.

.PUNCHOUTPUTORBITALS

PUNCH FINAL ORBITALS WITH LABEL **MOLORB, FORMAT (4F18.14). THESE ORBITALS MAY E.G. BE TRANSFERRED TO ANOTHER COMPUTER AND READ THERE WITH ".MOSTART" FOLLOWED BY " FORM18" ON NEXT LINE FROM THIS INPUT SECTION.

.REORDER

DEFAULT: NO REORDERING.

VERBATIM566#

REORDERING OF MOLECULAR ORBITALS (SEE COMMENTS).

.SUPSYM

DEFAULT IS NOSUPSYM.
ENFORCE AUTOMATIC IDENTIFICATION OF "SUPER SYMMETRY" (SEE COMMENTS).

.SYMMETRIC ORTHONORMALIZATION

DEFAULT: GRAM-SCHMIDT ORTHONORMALIZATION
SYMMETRIC ORTHONORMALIZATION OF INPUT ORBITALS.

.THRSSY

READ (LUINP,*) THRSSY
THRESHOLD FOR IDENTIFICATION OF "SUPER SYMMETRY" AND DEGENERACIES AMONG "SUPER SYMMETRIES" FROM MATRIX ELEMENTS OF THE KINETIC ENERGY MATRIX (DEFAULT: 5.0D-8).

COMMENTS:

IF ".SUPSYM" IS SPECIFIED, THEN SIRIUS AUTOMATICALLY IDENTIFIES "SUPER SYMMETRY", I.E. IT ASSIGNS ORBITALS TO THE IRREPS OF THE TRUE POINT GROUP OF THE MOLECULE WHICH IS A "SUPER GROUP" OF THE ABELIAN GROUP USED IN THE CALCULATION. DEGENERATE ORBITALS WILL BE AVERAGED AND THE "SUPER SYMMETRY" WILL BE ENFORCED IN THE ORBITALS. NOTE THAT "SUPER SYMMETRY" CAN ONLY BE USED IN THE RHF, MP2, MCSCF, AND RESPONS MODULES, AND SHOULD NOT BE INVOKED IF OTHER MODULES ARE USED, FOR EXAMPLE, IF **PROPERTIES (ABACUS) IS INVOKED. ALSO, IT CANNOT BE USED IN FINITE FIELD CALCULATIONS WHERE THE FIELD LOWERS THE SYMMETRY. THE INITIAL ORBITALS MUST BE SYMMETRY ORBITALS, AND THE SUPER SYMMETRY ANALYSIS IS PERFORMED ON THE KINETIC ENERGY MATRIX IN THIS BASIS. THE ".THRSSY" OPTION IS USED TO DEFINE WHEN THE KINETIC ENERGY MATRIX ELEMENT BETWEEN TWO ORBITALS IS CONSIDERED TO BE ZERO AND WHEN TWO DIAGONAL MATRIX ELEMENTS ARE DEGENERATE. IN THE FIRST CASE THE ORBITALS CAN BELONG TO DIFFERENT IRREPS OF THE SUPERGROUP AND IN THE SECOND CASE THE TWO ORBITALS ARE CONSIDERED TO BE DEGENERATE. THE ANALYSIS WILL FAIL IF THERE ARE ACCIDENTAL DEGENERACIES IN DIAGONAL ELEMENTS. THIS CAN HAPPEN IF THE NUCLEAR GEOMETRY DEVIATES SLIGHTLY FROM A HIGHER SYMMETRY POINT GROUP, FOR EXAMPLE BECAUSE TOO FEW DIGITS HAS BEEN USED IN THE INPUT OF THE NUCLEAR GEOMETRY. IF THE PROGRAM STOPS BECAUSE THE SUPER SYMMETRY ANALYSIS FAILS WITH A DEGENERACY ERROR, YOU MIGHT CONSIDER TO USE MORE DIGITS IN THE NUCLEAR COORDINATES, TO CHANGE THRSSY, OR TO DISABLE SUPER SYMMETRY BY NOT USING ".SUPSYM". THE VALUE OF THRSSY SHOULD BE SUFFICIENTLY SMALL TO AVOID ACCIDENTAL DEGENERACIES AND SUFFICIENTLY LARGE TO IGNORE SMALL ERRORS IN GEOMETRY AND NUMERICAL ROUND-OFF ERRORS.

.REORDER CAN FOR INSTANCE BE USED FOR LINEAR MOLECULES TO INTERCHANGE UNDESIRED DELTA ORBITALS AMONG THE ACTIVE ORBITALS IN SYMMETRY 1 WITH SIGMA ORBITALS. ANOTHER EXAMPLE IS MOVEMENT OF THE CORE ORBITAL TO THE RAS1 SPACE FOR CORE HOLE CALCULATION. IN GENERAL, USE OF THIS OPTION NECESSITATES A PRE-CALCULATION WITH STOP AFTER MO-ORTHONORMALIZATION AND IDENTIFICATION OF THE VARIOUS ORBITALS BY INSPECTION OF THE OUTPUT.