The GAMESS-UK Interface
Introduction
The GAMESS-UK interface permits the execution of relatively simple
GAMESS-UK jobs from within ChemShell. At present, the
functionality is limited to energy and gradient calculations,
implemented through the gamess families of Tcl procedures.
These routines conform to the general
energy/gradient interface In addition, a primitive interface is
provided to access the DMA analysis code, and more general
calculations can be performed if some specific GAMESS-UK directives
are provided.
gamess.energy, gamess.grad etc.
The gamess routines are used to provide energies and
gradients for use both directly in geometry optimisation etc,
and for hybrid QM/MM calculations for a number of different wave
functions.
The functions implemented include gamess.init,
gamess.energy, gamess.eandg, gamess.gradient,
gamess.hess and gamess.kill. The first and last of
these are dummy routines provided only for compatibility with other
codes that use the same energy/gradient interface.
| Argument |
Argument type |
Mandatory |
Default |
To specify |
| basis= |
keyword |
no |
sto3g |
basis set from GAMESS-UK internal library |
| basisfile= |
file |
no |
undefined |
file containing explicit basis definition |
| ecpfile= |
file |
no |
undefined |
file containing explicit definition for ECPs |
| charge= |
integer |
no |
0 |
system charge |
| mult= |
integer |
no |
1 |
spin multiplicity (as GAMESS-UK MULT directive) |
| dipole= |
Matrix tag
|
no |
undefined |
resultant dipole moment (au) |
| executable= |
string |
no |
set by environment |
name of the GAMESS-UK executable |
| list_option |
Output keyword
|
no |
medium |
How much output to generate |
| listing= |
file |
no |
gamess1.out |
file for listing gamess output |
| punchfile= |
file |
no |
gamess.pun |
punch file name |
| integ= |
file |
no |
gamess1.ed2 |
File to store the two-electron integrals |
| memory= |
integer |
no |
2000000 |
main memory request in words (8 bytes) |
| adaption= |
Boolean
|
no |
yes |
switch on/off of symmetry adaption of orbitals |
| symmetry= |
Boolean
|
no |
yes |
switch on/off use of symmetry |
| accuracy= |
keyword |
no |
undefined |
integral accuracy: low, medium, high, veryhigh, ultrahigh |
| direct= |
Boolean
|
no |
no |
switch on/off direct mode (see note 2) |
| scftype= |
rhf/uhf |
no |
undefined |
SCF type, see note 1 |
| wfntype= |
scf/ci/mcscf |
no |
scf |
wavefunction type |
| hamiltonian= |
keyword |
no |
hf |
Type of hamiltionian: hf, dft |
| functional= |
keyword |
no |
none |
DFT functional (Gamess keyword). Mandatory if hamiltonian=dft |
| dft_keywords= |
Tcl List
|
no |
undefined |
GAMESS-UK DFT control directives (see note 3) |
| restart= |
Boolean
|
no |
see note 4 |
whether to attempt to start from old wavefunction |
| scf_keywords= |
Tcl List
|
no |
undefined |
GAMESS-UK SCF control directives, can also include control
directives for the newscf module.
|
| open_shells= |
string |
no |
empty string |
GAMESS-UK open directive |
| scf_thresh= |
integer |
no |
1.e-5 |
threshold for SCF convergence |
| maxcyc= |
integer |
no |
undefined |
maximum number of SCF iterations |
| corr_thresh= |
real |
no |
undefined |
threshold for CI convergence |
| corr_maxcyc= |
integer |
no |
undefined |
maximum number of CI iterations |
| level= |
string |
no |
undefined |
GAMESS-UK level-shift value |
| diis_test= |
real |
no |
undefined |
GAMESS-UK DIIS TEST setting |
| diis_onset= |
real |
no |
0.1 |
GAMESS-UK DIIS ONSET setting |
Some NOTES on the gamess arguments:
- SCFTYPE: Allowed scftype= arguments are:
- rhf
- rohf: An additional open_shells= argument must be specified
in case of an open-shell system
- uhf
- gvb: An additional open_shells= argument must be specified
in case of an open-shell system
- mcscf: An additional specification of frozen, core, doubly occupied,
alpha, beta, and unoccupied orbitals is expected
If no scftype= argument is specified, the ROHF-GVB driver will be called
for open-shell systems. GAMESS-UK supports only the highest spin-multiplicity
in this manner. For other spin-states, the scftype= argument must
be set explicitly, as well as the open-shell structure through the
open_shells= argument.
-
Where GAMESS-UK supports direct mode for a given wave-function, it may be requested using
direct=yes. For open-shell systems the scftype= argument must
be specified, as the default ``scft direct'' only supports the RHF
closed-shell wavefunction.
- DFT_KEYWORDS: The DFT options presently available in GAMESS-UK
are invoked by specifying the dft_keywords= argument. More than one argument
may be specified (except when dft_keywords= standard).
Currently, only the RHF wavefunction is available for all
exchange and correlation potentials; the UHF wavefunction is available only for
Dirac exchange (LDA) and VWN correlation potentials. Any keyword allowed by
gamess can be used. The density functional itself may also be specified using
the keywords hamiltonian= or functional=
- standard: standard option: Dirac exchange, VWN correlation, exact Coulomb integrals
- hfex: exact exchange
- lyp: LYP correlation potential
- blyp: Becke88 exchange functional plus LYP correlation functional
- bp86: Becke88 exchange and Perdew86 correlation functional (both gradient corrected)
- b3lyp: B3-LYP hybrid exchange-correlation potential
- nocorr: Omission of correlation potential
- screen: switch on screening in quadrature
(optionally followed by 3 tolerances for basis amplitude (1e-12),
density-matrix element (1e-10), and rho (1e-14), respectively
- If coulomb-fitting (called RI or density fitting in other codes) should be
used, which is highly recommended for functionals without Hartree-Fock
exchange, the following dft_keywords may be used: "JFIT memory JFITG" "JBAS ahlrichs"
- restart: By default restart=no is assumed for the first
GAMESS-UK calculation in a series (for example the first
point in an optimisation) and restart=yes is assumed thereafter.
Arguments controlling CI Calculations
| Argument |
Argument type |
Mandatory |
Default |
To specify |
| ci_core= |
string |
no |
empty string |
GAMESS-UK CORE directive for MRCI |
| ci_active= |
string |
no |
empty string |
GAMESS-UK ACTIVE directive for MRCI |
| ci_defs= |
string |
no |
empty string |
GAMESS-UK DIRECT directive |
| ci_conf= |
string |
no |
empty string |
configurations in MRCI |
Arguments controlling MCSCF Calculations
| Argument |
Argument type |
Mandatory |
Default |
To specify |
| num_fzc= |
integer |
no |
0 |
number of frozen-core orbitals in MCSCF calculation |
| num_cor= |
integer |
no |
0 |
number of core orbitals in MCSCF calculation |
| num_doc= |
integer |
no |
0 |
number of doubly occupied orbitals in MCSCF calculation |
| num_alp= |
integer |
no |
0 |
number of alpha orbitals in MCSCF calculation |
| num_bet= |
integer |
no |
0 |
number of beta orbitals in MCSCF calculation |
| num_uoc= |
integer |
no |
0 |
number of unoccupied orbitals in MCSCF calculation |
| Argument |
Argument type |
Mandatory |
Default |
To specify |
| iter |
integer |
no |
not spec. |
iter=0 causes a normal QM calculation
and (R)ESP charges fitted to the obtained density afterwards. iter=1 skips the
QM calculation and calculates the electrostatic interaction with bq-charges
from the (R)ESP charges. |
| esp_npoint |
integer |
no |
-1 |
Number of points to fit the potential. Negative
values mean twice the number of QM atoms, see
get_esp_points |
| esp_type |
keyword |
no |
shell |
mmatoms leads to a fit of the potential at the
nearest MM atoms, shell leads to a fit at a shell around the QM atoms, see
get_esp_points |
| esp_method |
keyword |
no |
esp |
resp causes RESP charges to be calculated, see
fit_esp_charges |
General GAMESS-UK calculations
To take advantage of functionality within
GAMESS-UK other than that addressed by the gamess functions
described above, the command gamess.calc may be invoked.
The following arguments are compulsory to gamess.calc:
| Argument |
Argument type |
To specify |
| coords= |
fragment |
cartesian coordinates of
molecule |
| energy= |
file |
file containing computed energy |
| gradient= |
file |
file containing computed gradient |
The arguments given in the previous section may all be used. In addition, the following
arguments specify further control information.
| Argument |
Argument type |
To specify |
| mode= |
keyword |
type of calculation to perform - (see below) |
| control= |
file |
file containing gamess runtype and associated directives |
| punchcontrol= |
file |
file containing punch directives |
| bypass= |
keyword |
bypass option ( may be ``old'' or ``two'') |
| chargefield= |
file |
file containing point charge array |
| adaption= |
keyword |
symmetry adaption of integrals
(default on |
| symmetry= |
keyword |
use of highest possible symmetry
(default on |
| maxcyc= |
integer |
maximum number of SCF cycles |
The valid settings for the mode= argument are given in the
table below.
| Keyword |
Calculation |
| scf-startup |
SCF calculation |
| scf-restart |
SCF calculation, given pre-existing dumpfile |
| grad-startup |
SCF and gradient |
| grad-restart |
gradient, from pre-computed SCF |
| dma-restart |
DMA, for pre-computed SCF step |
| hess-startup |
Analytic second derivatives |
| hess-restart |
Analytic second derivatives, from pre-computed SCF |
| general |
General purpose option (directives taken from control file) |
| general-restart |
As general, but assuming pre-converged SCF |
general Mode
This option is provided to allow for types of calculations which do
not correspond to one of the modes described above. To use the general
mode, knowledge of the GAMESS-UK input file structure is required.
You must create a file containing the RUNTYPE directive for the job
step you require, followed by any directives specific to the calculation.
You do not need to include VECTORS or ENTER.
The Newscf Module
The newscf module can be driver using the scf_options=
argument. There is some brief documentation
on the control information needed for this module.
Limitations
There are many limitations to this interface, among those that are most likely
to cause problems are flagged up to avoid confusion.
- No control for vector routing on the dumpfile.
- General mode does not allow geometry specification in z-matrix form
- Results generated in general mode will not usually be available for
further use within ChemShell.
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