$GUESS group (optional, relevant for all SCFTYP's) This group controls the selection of initial molecular orbitals. GUESS = Selects type of initial orbital guess. = HUCKEL Carry out an extended Huckel calculation using a Huzinaga MINI basis set, and project this onto the current basis. This is implemented for atoms up to Rn, and will work for any all electron or core potential basis set. (default for most runs) = HCORE Diagonalize the one electron Hamiltonian to obtain the initial guess orbitals. This method is applicable to any basis set, but does not work as well as the HUCKEL guess. = MOREAD Read in formatted vectors punched by an earlier run. This requires a $VEC deck, and you MUST pay attention to NORB below. = RDMINI Read in a $VEC deck from a converged SCF calculation using GBASIS=MINI, to project the MINI orbitals onto the current basis. The option improves upon the Huckel guess because it involves SCF orbitals, which are typically easily obtained in the small MINI basis. This option doesn't work if the current basis uses core potentials. potentials. The $VEC from the MINI run must contain all virtual orbitals. = MOSAVED (default for restarts) The initial orbitals are read from the DICTNRY file of the earlier run. = SKIP Bypass initial orbital selection. The initial orbitals and density matrix are assumed to be in the DICTNRY file. Mostly used for RUNTYP=HESSIAN when the hessian is being read in from the input. The next options are less general, being for Fragment Molecular Orbital runs, or Divide and Conquer runs: = FMO Read orbitals from the DICTNRY file, from previous FMO run with MODPRP=1. = HUCSUB Perform a Huckel guess in each subsystem of a Divide and Conquer run = DMREAD Read a density matrix from a formatted $DM group, produced by a previous Divide and Conquer run, see NDCPRT in $DANDC. All GUESS types except 'SKIP' permit reordering of the orbitals, carry out an orthonormalization of the orbitals, and generate the correct initial density matrix, for RHF, UHF, ROHF, and GVB, but note that correct computation of the GVB density requires also CICOEF in $SCF. The density matrix cannot be generated from the orbitals alone for MP2, CI, or MCSCF, so property evaluation for these should be RUNTYP=ENERGY rather than RUNTYP=PROP using GUESS=MOREAD. PRTMO = a flag to control printing of the initial guess. (default=.FALSE.) PUNMO = a flag to control punching of the initial guess. (default=.FALSE.) MIX = rotate the alpha and beta HOMO and LUMO orbitals so as to generate inequivalent alpha and beta orbital spaces. This pertains to UHF singlets only. This may require use of NOSYM=1 in $CONTRL depending on your situation. (default=.FALSE.) NORB = The number of orbitals to be read in the $VEC group. This applies only to GUESS=MOREAD. For -RHF-, -UHF-, -ROHF-, and -GVB-, NORB defaults to the number of occupied orbitals. NORB must be given for -CI- and -MCSCF-. For -UHF-, if NORB is not given, only the occupied alpha and beta orbitals should be given, back to back. Otherwise, both alpha and beta orbitals must consist of NORB vectors. NORB may be larger than the number of occupied MOs, if you wish to read in the virtual orbitals. If NORB is less than the number of atomic orbitals, the remaining orbitals are generated as the orthogonal complement to those read. NORDER = Orbital reordering switch. = 0 No reordering (default) = 1 Reorder according to IORDER and JORDER. IORDER = Reordering instructions, giving the new molecular orbital order. This parameter applies to the common orbitals (both alpha and beta) except for UHF, where IORDER only affects the alpha MOs. Examples (let there be 10 occupied orbitals): transposition of HOMO and LUMO: IORDER(10)=11,10 a different transposition: IORDER(10)=15 IORDER(15)=10 a more general permutation: IORDER(8)=11,8,9,10 so the new orbital 10 is the original 9th. The default is IORDER(i)=i. JORDER = Reordering instructions. Same as IORDER, but for the beta MOs of UHF. INSORB = the first INSORB orbitals specified in the $VEC group will be inserted into the Huckel guess, making the guess a hybrid of HUCKEL/MOREAD. This keyword is meaningful only when GUESS=HUCKEL, and it is useful mainly for QM/MM runs where some orbitals (buffer) are frozen and need to be transferred to the initial guess vector set, see $MOFRZ. (default=0) * * * the next are 3 ways to clean up orbitals * * * PURIFY = flag to symmetrize starting orbitals. This is the most soundly based of the possible procedures. However it may fail in complicated groups when the orbitals are very unsymmetric. (default=.FALSE.) TOLZ = level below which MO coefficients will be set to zero. (default=1.0E-7) TOLE = level at which MO coefficients will be equated. This is a relative level, coefficients are set equal if one agrees in magnitude to TOLE times the other. (default=5.0E-5) SYMDEN = project the initial density in order to generate symmetric orbitals. This may be useful if the HUCKEL or HCORE guess types give orbitals of impure symmetry (?'s present). The procedure will generate a fairly high starting energy, and thus its use may not be a good idea for orbitals of the quality of MOREAD. (default=.FALSE.) ========================================================== ==========================================================

generated on 7/7/2017