Guess=Only may not be used with the MOPAC-based semi-empirical methods (INDO, CNDO, MNDO, MINDO3). Note that the amount of orbital information that is printed is controlled by the Pop keyword. Guess=Only functions as a calculation type keyword and requests that the calculation terminate once the initial guess is computed and printed. See the discussion of the Population keyword for details. This must be accomplished via a separate job step specifying this option as well as Only and Save. Include natural orbitals in the checkpoint file. This option is also useful in the combination of Guess=(BiOrth,Read,Only,Save) to replace the canonical UHF orbitals with ones which have alpha and beta orbitals matched up as much as possible for viewing in GaussView or other visualization packages. Done automatically when a UHF wavefunction is read-in as a guess for ROHF.
Biorthogonalizeįor an unrestricted guess, biorthogonalize the α and β MOs to maximally pair electrons of opposite spin. Useful when importing from matrix element files. Cop圜hkĬopy the MOs and density unedited, unprojected and unchecked from the checkpoint file for the guess. N defaults to -3 (use Huckel eigenvalues to decide which orbitals to mix). Whether to mix occupied and virtual orbital contributions in forming the initial guess density. Mixing orbitals is only done by default when generating a complex initial guess. This is useful in producing UHF wavefunctions for singlet states.
Requests that the HOMO and LUMO be mixed so as to destroy α-β and spatial symmetries. The second blank line to indicate an empty β section must be included. Thus, even if only α transpositions are needed, the β section is required even though it is empty (and vice-versa). The list of orbital transpositions is terminated by the blank line at the end of the input section.įor UHF calculations, two such orbital alteration sections are required, the first specifying transpositions of α orbitals and the second specifying transpositions of β orbitals. Each such transposition is on a separate line and has two integers N 1 and N 2 (free format, separated by spaces or a comma as usual) indicating that orbital N 1 is to be swapped with orbital N 2. The alteration sections consist of a set of transpositions indicating that one of these occupied orbitals is to be replaced by one of the other (virtual) orbitals. Normally, the occupied orbitals are selected as those with lowest eigenvalues for the one-electron Hamiltonian used in the initial guess programs. Indicates that the orbitals selected for occupation in the Hartree-Fock wavefunction should not be those of lowest energy. Separate permutation lists for α and β orbitals must be specified (each list separated by a blank line) for open shell systems. 7–12) can be used, and all orbitals not listed are put in after the listed orbitals in their original order. The numbers of the generated guess orbitals are given in the order in which they should be used in the SCF. Read in a permutation of orbitals in the initial guess. TightConvergenceĬhange the defaults to 10 -10 convergence on SCF and 10 -8 for CIS, TD and CC. This is the default for AM1, PM3, PM3MM, PM6, and PDDG. Requests that the core Hamiltonian be diagonalized to form the initial guess. Guess=(AM1,Always) causes later steps in a geometry optimization to generate a new guess at each point and compare the energies with the density from the old point and the new guess and take the best one.
AM1ĭo an AM1 calculation for the initial guess (currently only works with sparse matrix code).
Use the Gaussian 98 default guess: INDO for first-row systems, CNDO for second-row, and Huckel for third-row and beyond. Use the old Huckel guess (pre-Gaussian 03) instead of CNDO or the updated Huckel. Read in the scale factor on atomic hardnesses used in iterative extended Huckel. The Huckel guess should be considered for PM6 calculations involving many second-row atoms. This is the default for CNDO, INDO, MNDO, and MINDO3. Requests that a Huckel guess be generated. This is the default for all HF and DFT calculations. Diagonalize the Harris functional for the initial guess.
0 kommentar(er)
