$DANDC group (optional, relevant if SCFTYP=RHF or UHF) This group controls the divide-and-conquer (DC) SCF calculations, in which the total 1-electron density matrix is obtained as sum of subsystem density matrices. In this calculation, the total system is partitioned into several disjoint subsystems (central regions). A subsystem density matrix is expanded by bases in the central region and its neighboring environmental region (buffer). The present implementation allows energy and analytic nuclear gradients, for HF, DFT, and semi-empirical runs, for SCFTYP=RHF or UHF only. The discrete EFP and various continuum solvation models are available. DC correlation energies are also available for either MP2 and CC, see $DCCORR, without nuclear gradients. Dynamic and static polarizabilities (but no hyperpolarizabilities) based on DC-HF are available by specifying RUNTYP=TDHF (not TDHFX). The initial guess is given by a density matrix, not orbitals. The only available options are GUESS=HUCKEL, HCORE, HUCSUB, DMREAD, and MOREAD (the latter means orbitals for the entire system). For a review paper on Divide-and-Conquer in GAMESS: M.Kobayashi, H.Nakai in Linear-Scaling Techniques in Computational Chemistry and Physics: Methods and Applications (Springer), Chap. 5 (2011) For more information on the DC-SCF method, see W.Yang, T.-S.Lee J.Chem.Phys. 103, 5674-5678(1995) T.Akama, M.Kobayashi, H.Nakai J.Comput.Chem. 28, 2003-2012(2007) T.Akama, A.Fujii, M.Kobayashi, H.Nakai Mol.Phys. 105, 2799-2804(2007) T.Akama, M.Kobayashi, H.Nakai Int.J.Quant.Chem. 109, 2706-2713(2009) M.Kobayashi, T.Yoshikawa, H.Nakai Chem.Phys.Lett. 500, 172-177(2010) [open-shell] M.Kobayashi, T.Kunisada, T.Akama, D.Sakura, H.Nakai J.Chem.Phys. 134, 034105/1-11(2011) [gradient] For more information on DC-MP2 and DC-CC, see M.Kobayashi, Y.Imamura, H.Nakai J.Chem.Phys. 127, 074103/1-7(2007) M.Kobayashi, H.Nakai J.Chem.Phys. 129, 044103/1-9(2008) M.Kobayashi, H.Nakai J.Chem.Phys. 131, 114108/1-9(2009) M.Kobayashi, H.Nakai Int.J.Quant.Chem. 109, 2227-2237(2009) For more information on DC-TDHF polarizability, see T.Touma, M.Kobayashi, H.Nakai Chem.Phys.Lett. 485, 247-252(2010) Of course, the trick to methods that divide up a large problem into small ones is to control the errors that result. A simple way to set up a DC-MP2 calculation is with atomic partitions: $contrl scftyp=rhf mplevl=2 runtyp=energy $end $system mwords=25 $end $scf dirscf=.true. $end $dandc dcflg=.true. subtyp=atom bufrad=8.0 $end $dccorr dodccr=.true. rbufcr=5.0 $end $guess guess=hucsub $end (if DC-SCF is used) This leads to as many subsystems as there are atoms, with the buffer region around the central atom being defined by a radius. This input recognizes that exchange effects in Hartree-Fock are longer range than correlation, and thus uses dual level radii. It may be reasonable to simply do a conventional and thus fully accurate SCF computation by DCFLG=.FALSE., obtaining only the MP2 correlation energy by the divide and conquer method. Faster run times may result from other partitionings, such as manually dividing a protein into subsystems containing a single amino acid. DCFLG = flag to activate DC-SCF calculation. (default=.FALSE.) Note: If you want to treat only the correlated MP2/CC procedure in the DC manner, after a standard HF calculation, this option may be set to .FALSE. SUBTYP = chooses a method to construct disjoint subsystems (central region). = ATOM individual atom is 1 subsystem. (default if NSUBS=0 or not given) = MANUAL manually selects using NSUBS and LBSUBS keywords. (default if NSUBS>=1) = CARD reads from card. $SUBSCF is used for SCF and $SUBCOR for MP2/CC calculation. = AUTO constructs subsystems automatically by dividing total system by cubic grid. Grid size can be set by SUBLNG. = AUTBND considers bond strength after AUTO. NSUBS = number of subsystems when SUBTYP=MANUAL. LBSUBS = an array assigning atoms to subsystems. The style is the same as INDAT keyword in $FMO. Two styles are supported (the choice is made based on LBSUBS(1): if it is nonzero, choice (a) is taken, otherwise LBSUBS(1) is ignored and choice (b) is taken): a) LBSUBS(i)=m assigns atom i is to subsystem m. LBSUBS(i) must be given for each atom. b) the style is a1 a2 ... ak 0 b1 b2 ... bm 0 ... Elements a1...ak are assigned to subsystem 1, then b1...bm are assigned to subsystem 2,etc. An element is one of the following: I or I -J where I means atom I, and a pair I,-J means the range of atoms I-J. There must be no space after the "-"! Example: LBSUBS(1)=1,1,1,2,2,1 is equivalent to LBSUBS(1)=0, 1,-3,6,0, 4,5,0 Both assign atoms 1,2,3 and 6 to subsystem 1, and 4,5 to subsystem 2. SUBLNG = grid length of cube used in SUBTYP=AUTO or AUTBND. This value should be in the unit given by UNITS keyword in $CONTRL. (default=2.0 Angstroms). BUFTYP = chooses a method to construct buffer region. = RADIUS selects atoms included in spheres centered at atoms in the central region (default). The radius is given by BUFRAD keyword for DC-SCF and by the RBUFCR keyword in $DCCORR for DC-MP2/CC. = RADSUB selects subsystems containing one or more atom(s) which is included in spheres centered at atoms in the central region. This selection can avoid cutting bonds within each subsystem. = CARD reads from $SUBSCF or $SUBCOR card. Only available when SUBTYP=CARD. BUFRAD = buffer radius in DC-SCF calculation. This value should be in the units given by UNITS keyword in $CONTRL (default=5.0 Angstroms). FRBETA = inverse temperature parameter of Fermi function used in DC-SCF procedure in a.u. (default=200.0) Reducing this value may improve SCF convergence but may obtain worse total energy. MXITDC = maximum number of iteration cycles for determining Fermi level (default=100). Usually, you need not care about this keyword. FTOL = Fermi function cutoff factor (default=15.0). = p The value of Fermi function less than 10**(-p) is considered as 0. The value greater than [1 - 10**(-p)] is considered as 1. NDCPRT = DC print-out option which is the sum of followings (default=0). = +1 not used (reserved). = +2 prints density matrix ($DM section) on punch. = +4 prints energy corresponding to each subsystem. Gives correct energy only in HF calculation. = +8 prints orbitals in each subsystem. IORBD = selects molecular orbital in total system whose electron density is to be computed. Print format is given in $ELDENS. = -1, -2, ... correspond to HOMO, HOMO-1, ... = 1, 2, ... correspond to LUMO, LUMO+1, ... = 0 no calculation (default). In the DC-SCF procedure, the available SCF acceleration techniques are DIIS, DAMP, EXTRAP as well as DC-DIIS and VFON which are specific to the DC-SCF. In DC-SCF calculation, only DIIS is used by default. DC-DIIS (DIIDCF=.TRUE.) is not normally needed for convergence. The following keywords control (DC-)DIIS convergence: DIITYP = selects the error vector used in the standard DIIS extrapolation = FDS Pulay's modified DIIS (e=FDS-SDF). Although this type of error vector behaves well in standard SCF, it may not for DC-SCF. = DELTAF Pulay's original DIIS (e[i]=F[i]-F[i-1]), or so-called Anderson mixing (default). DIIQTR = .TRUE. uses orthogonal basis (in entire system) for DIIS extrapolation. Normally, this does not make sense in DC-SCF run. .FALSE. uses atomic basis function for DIIS extrapolation (default). EXTDII = energy error threshold in absolute value for exiting DIIS (default=0.0). PEXDII = percentage threshold of energy error change for exiting DIIS (default=1.0). PEXDII is preferential to EXTDII. DIIDCF = a flag to activate DC-DIIS interpolation (default=.FALSE.). ETHRDC = energy error threshold for initiating DC-DIIS. Increasing ETHRDC forces DC-DIIS on sooner (default = 1.D-4 if DIIDCF=.TRUE.). The following keywords control the convergence acceleration based on the varying fractional occupation number (VFON). The final electronic temperature is given by FRBETA. FONTYP = selects the variation pattern of electronic temperature (beta) in SCF iteration = DIIER logarithmic variation with respect to DIIS error. = NONE no variation (default). BETINI = initial beta value in a.u. (default = FRBETA/4 for FONTYP=DIIER). FONSTA = threshold to start variation of beta (default=1.0 for FONTYP=DIIER). FONEND = threshold to stop variation of beta (default=1.D-4 for FONTYP=DIIER). When FONTYP=DIIER, the beta value used in the iteration (of which the DIIS error is DIISer) is the following: beta = BETINI [for DIISER>FONSTA] = FRBETA [for DIISER<=FONEND] = FRBETA + C_FON * Log(DIISer/FONEND) [otherwise] where (C_FON = (BETINI-FRBETA) / Log(FONSTA/FONEND) Option for the type of nuclear gradient: NDCGRD = selects the DC-SCF gradient implementation = 0 use a formula proposed by Yang and Lee in 1995 = 1 use a formula proposed by Kobayashi et al. in 2011 (default) Next are options for printing density of states (DOS). DOSITV = Interval between plot points in Hartree. The default is zero,meaning no DOS print-out. If you print out DOS, DOSITV=0.05 may be sufficient. DOSRGL = Left end of the plot range in Hartree. (default=-2.0) DOSRGR = Right end of the plot range in Hartree. (default=+2.0) BDOS = Inverse temperature parameter (beta) for distributing states. This value should not be given because it is set to be equivalent to FRBETA in $DANDC by default. ========================================================== ==========================================================

generated on 7/7/2017