$EFRAG group (optional) The Effective Fragment Potential (EFP) is a potential extracted from rigorous quantum mechanics, permitting the treatment of solvent molecules (or other types of subsystems) with a potential. There are two models, EFP1 and EFP2, with more accurate physics in the latter. For more information, see chapter 4 of this manual. EFP1 calculations are typically limited to a QM system with water molecules, the latter modeled by RHF-based or DFT-based potentials which are built into the program. The following EFP1/QM calculations are possible: QM/EFP1 method1 method2 SCF RHF (and DFT) gradient x UHF (and DFT) gradient x ROHF(and DFT) gradient x MP2(RHF/UHF/ROHF) gradient x x CCSD energy x x CCSD(T) energy x CR-CCL energy x EOM-CCSD energy x x CR-EOML energy x CITYP=CIS (only) gradient x x TDDFT(RHF) gradient x x GVB gradient x MCSCF gradient x Here, SCF means the QM calculation and the EFP particle's polarizability terms are made fully self-consistent. Otherwise, the QM density felt by the EFP particles is that of the reference (ground) state, termed "method 1". A more accurate and detailed energy calculation is possible when the QM's density is available for a specific correlation treatment and/or a specific excited state. Such "method 2" calculations are available only for RUNTYP=QMEFPEA. The "method 1" calculations can be used for any relevant run type using the energy or analytic nuclear gradients, as indicated. For example, after MP2 geometry optimization, numerical differentiation can produce solvated MP2-level frequencies. EFP2 calculations should use COORD=FRAGONLY at the present time, as the QM/EFP2 interaction terms are currently under active development. The programming for EFP2/EFP2 interactions is completed. See RUNTYP=MAKEFP to create EFP2 potentials. In most cases, the entire EFP1, QM/EFP1, or EFP2 system can be embedded in a PCM continuum (see $PCM). This group gives the name and position of one or more effective fragment potentials. It consists of a series of free format card images, which may not be combined onto a single line! The position of a fragment is defined by giving any three points within the fragment, relative to the ab initio system defined in $DATA, since the effective fragments have a frozen internal geometry. All other atoms within the fragment are defined by information in the $FRAGNAME input group. ---------------------------------------------------------- -1- a line containing one or more of these options: If you choose more options than are able to be fit on a single 80 character line, type an > character to continue onto the next line. If you do not choose any of these options, input a blank line to accept defaults. COORD =CART selects use of Cartesians coords to define the fragment position at line -3-. (default) =INT selects use of Z-matrix internal coordinates at line -3-. POLMETHD=SCF indicates the induced dipole for each fragment due to the ab initio electric field and other fragment fields is updated only once during each SCF iteration. =FRGSCF requests microiterations during each SCF iteration to make induced dipoles due to ab initio and other fragment fields self consistent among the fragments. (default) Both methods converge to the same dipolar interaction. POSITION=OPTIMIZE Allows full optimization within the ab initio part, and optimization of the rotational and translational motions of each fragment. (default) =FIXED Allows full optimization of the ab initio system, but freezes the position of the fragments. This makes sense only with two or more fragments, as what is frozen is the fragments' relative orientation. FIXED may be used with RUNTYP being OPTIMIZE, SADPOINT, HESSIAN and IRC. =EFOPT the same as OPTIMIZE, but if the fragment gradient is large, up to 5 geometry steps in which only the fragments move may occur, before the geometry of the ab initio piece is relaxed. This may save time by reusing the two electron integrals for the ab initio system. NBUFFMO = n First n orbitals in the MO matrix are deemed to belong to the QM/MM buffer and will be excluded from the interaction with the EFP region. This makes sense only if these first MOs are frozen via the $MOFRZ. The next few inputs apply periodic boundary conditions, which is only possible if the system contains only EFP particles, with no ab initio atoms. The default is to use the minimum image convention, for all terms in the potentials, but see also the $EWALD input group in order to perform the long range electrostatic interactions in a more accurate manner. You may choose no more than one of the possible sets of cutoffs, with the switching function SWR1/SWR2 being the most physically reasonable. XBOX, YBOX, ZBOX = dimensions of the periodic box, which must be given in Angstroms. If these sizes are omitted, the simulation is an isolated cluster. SWR1, SWR2 = distance cutoffs for the switching function that gradually drops the interactions from full strength at SWR1 to zero at SWR2. Choose SWR2 <= min(XBOX/2,YBOX/2,ZBOX/2) and SWR1 <= SWR2 (typically 80%), to cut off interactions within a single box. In Angstrom RCUT a radial cutoff, implemented as a step function, which should be chosen like SWR2. In Angstrom XCUT, YCUT, ZCUT = cutoffs (as step functions) beyond which effective fragment potential interactions are not computed, XCUT <= XBOX/2, etc. Angstroms For a simulation of 64 CCl4 molecules, PBC input might be xbox=21.77 ybox=21.77 zbox=21.77 swr1=8.0 swr2=10.0 Box sizes are typically chosen to give a correct value for the density of the system. The following turn off selected terms in the potentials, even if data for the term is found in the various $FRAGNAME input groups. These keywords are standalone strings, without a value assigned to them. They allow data from potentials generated by MAKEFP runs to be kept in the $FRAGNAME, for possible future use. The first two are of interest in production runs, while the others are primarily meant for debugging purposes, as the latter terms are normally quite large. NOCHTR = switch off charge transfer in EFP2 NODISP = switch off dispersion in EFP2 NOEXREP = switch off exchange repulsion (EFP1/EFP2) NOPOL = switch off polarization (implies NOPSCR) NOPSCR = switch off polarization screening, only The following parameters are related to screening of some terms in the potentials, when fragments are at close distances. Note that they are relevant only to EFP2 runs. Prior to May 2009, the defaults were ISCRELEC=0 ISCRPOL=0 ISCRDISP=0 at which time the defaults were changed to ISCRELEC=0 ISCRPOL=1 ISCRDISP=1 If you need to reproduce results or continue an ongoing set of computations, simply input the old defaults. ISCRELEC = fragment-fragment electrostatic screening, a correction for "charge penetration": E(elec) = E(multipoles) + E(chg.pen.) = 0 damping by various formulae is controlled by SCREEN1, SCREEN2, or SCREEN3 input sections in the $FRAGNAME input(s). If none are found, there will be no charge penetration screening of electrostatics. (default) = 1 use an overlap based damping correction E(chg.pen.)= -2(S**2/R)/sqrt(-2ln|S|) to the classical multipole energy. Since the overlap integrals used here, as well as in ISCRDISP must be evaluated as part of the exchange repulsion energy, there is essentially no overhead for selecting this. ISCRPOL = fragment-fragment polarization screening. = 0 damping is controlled by POLSCR sections in the $FRAGNAME inputs. If not found, there will be no screening. If POLSCR is found, you must also use ISCRELEC=0 and SCREEN3. = 1 damping will use a Tang-Toennis style Gaussian formula, (1-exp(aR**2)(1+aR**2) where the default value of a=0.6. In order to change the 'a' parameter, give POLAB STOP in the $FRAGNAME input. A smaller value may be useful for ionic EFPs. (default) ISCRDISP = fragment-fragment dispersion screening = 0 Use Tang-Toennies damping, with a fixed parameter a=1.5. = 1 use an overlap based damping factor, 1-S**2(1-2ln|S|+2ln**2|S|) instead. There is no parameterization, so there's no other input. (default) It is possible to choose ISCRELEC, ISCRPOL, and ISCRDISP independently, as they apply to distinct parts of the fragment-fragment effective potential, and apart from POLSCR/SCREEN3, are independently implemented. FRCPNT this keyword activates decomposing and printing the forces at the desired points in the EFP fragments, in additional to the traditional summing of the forces at the fragments' center-of-masses. This is useful for coarse graining the EFP data. If this option is selected, FORCE POINT section(s) must be given in the $FRAGNAME input(s). The following keywords are for use with the EFP2-AI (a.k.a. EFP2-QM) dispersion calculation, that is, the calculation of the dispersion energy in a mixed system containing one or more EFP2 fragment(s) and a molecule modeled with a fully ab initio method (e.g. Hartree-Fock). QMDISP specify whether to perform the calculation of EFP2-AI dispersion = 0 do not calculate dispersion, even if both an EFP2 fragment and an ab initio part are present (default) = 1 perform the EFP2-AI dispersion calculation ISCRQMDS specify type of screening to use with EFP2-AI damping =-1 turn off damping (for debugging or benchmark comparison purposes) = 0 use Tang-Toennies damping, with a fixed parameter a=1.5 = 1 use a parameter-free, overlap-based damping factor, 1-S**2(1-2ln|S|+2ln**2|S|) (default) NODSGRD skip calculation of the EFP2-AI dispersion gradient, even if a gradient calculation is specified with RUNTYP=GRADIENT Note that localized orbitals are necessary for the dispersion energy calculation. Boys localization will be performed by default if QMDISP=1 is specified, with no additional input keywords necessary. An alternate localization method may be specified using the LOCAL keyword in $CONTRL. NIDISP7 skip computating the 7th power dispersion. ---------------------------------------------------------- -2- FRAGNAME=XXX XXX is the name of the fragment whose coordinates are to be given next, and whose potential may also be in the input stream, as $XXX groups. XXX may not exceed 6 characters. Below, the actual $XXX groups are referred to generically as $FRAGNAME. Specific examples of $FRAGNAME are $C6H6, $BENZEN, $DMSO, ... All information defining the EFP2-type fragment potential is given in its $FRAGNAME. A few standard EFP2 potentials are provided: see ~/gamess/auxdata/EFP. These are used by placing the desired file(s) into your input. Two different EFP1-type water potentials are internally stored. FRAGNAME=H2ORHF will select a water potential developed at the RHF/DZP level, while FRAGNAME=H2ODFT will select a potential corresponding to B3LYP/DZP (see $BASIS for the precise meaning of DZP). If you choose either of these internally stored potentials, you need not give any further input to define them. Since the EFP model consists of distributed multipoles and distributed polarizabilities, it is trivial to map some of the literature's simplified water potentials onto the EFP1 programming. For example, the octupole expansions used in EFP can be truncated to point charges (monopole term). So, FRAGNAME may also be any of the following water models: SPC, SPCE, TIP5P, TIP5PE, or POL5P Their EFP/EFP repulsion term is a typical 6-12 Lennard- Jones form. Repulsion between the QM and EFP particles follows the EFP1 style, if any QM atoms are input. ---------------------------------------------------------- -3- NAME, X, Y, Z (COORD=CART) NAME, I, DISTANCE, J, BEND, K, TORSION (COORD=INT) NAME = the name of a fragment point. The name used here must match one of the points in $FRAGNAME. For the internally stored H2ORHF and H2ODFT potential, the atom names are O1, H2, and H3. X, Y, Z = Cartesian coordinates defining the position of this fragment point RELATIVE TO THE COORDINATE ORIGIN used in $DATA. The choice of units is controlled by UNITS in $CONTRL. I, DISTANCE, J, BEND, K, TORSION = the usual Z-matrix connectivity internal coordinate definition. The atoms I, J, K must be atoms in the ab initio system from in $DATA, or fragment points already defined in the current fragment or previously defined fragments. If COORD=INT, line -3- must be given a total of three times to define this fragment's position. If COORD=CART, line -3- must be given three times, which is sufficient to orient the rigid EFP particle. However, it is good form to read in any remaining nuclei in the EFP, for example all 12 atoms in a benzene EFP, although only the first three lines determine the entire EFP's position, whenever you have the data for the extra nuclei. ---------------------------------------------------------- Repeat lines -2- and -3- to enter as many fragments as you desire, and then end the group with a $END line. Note that it is quite typical to repeat the same fragment name at line -2-, to use the same type of fragment system at many different positions. ========================================================== * * * * * * * * * * * * * * * * * * * * * For tips on effective fragment potentials see the 'further information' section * * * * * * * * * * * * * * * * * * * * * ==========================================================

generated on 7/7/2017