IntegralThe
Integral keyword modifies the method of computation and use of two-electron
integrals and their derivatives. INTEGRATION GRID SELECTION OPTIONGrid=grid
Specifies the integration grid to be used for numerical integrations. Note that
it is very important to use the same grid for all calculations where you
intend to compare energies (e.g., computing energy differences, heats of formation,
and so on). The parameter to this option is either a grid name keyword or a specific
grid specification. If a keyword is chosen, then the option name itself may be
optionally omitted (i.e, Integral(Grid=FineGrid) and Integral(FineGrid)
are equivalent). "Pruned" grids are grids that have been optimized to use
the minimal number of points required to achieve a given level of accuracy. Pruned
grids are used by default when available (currently defined for H through Kr). The
default grid is a pruned (75,302) grid, having 75 radial shells and 302 angular
points per shell, resulting in about 7000 points per atom; the value FineGrid
is used to specify this grid. Other grids may be selected by giving an integer
value N as the argument to Grid. Grid=UltraFine requests
a pruned (99,590) grid. It is recommended for molecules containing lots of tetrahedral
centers and for computing very low frequency modes of systems. Other special
values for this parameter are CoarseGrid, which requests a pruned version
of the (35,110) grid, and SG1Grid, a pruned version of (50,194). Note,
however, that the FineGrid has considerably better numerical accuracy and
rotational invariance than these grids, and they are not recommended for
production calculations [511]. Pass0Grid
requests the obsolete pruned (35,110) grid once intended for pass 0 of a tight
SCF calculation. Specific grids may be selected by giving an integer value
N as the argument to Grid. N may have one of these forms: A large
positive integer of the form mmmnnn, which requests a grid with mmm
radial shells around each atom, and nnn angular points in each shell. The
total number of integration points per atom is thus mmm*nnn. For example,
to specify the (99,302) grid, use Int(Grid=99302). The valid numbers of
angular points are 38, 50 [512], 72 [513],
86, 110 [512], 146, 194, 302 [514],
434 [515], 590, 770, and 974 [516].
If a larger number of angular points is desired, a spherical product grid can
be used. A large negative integer of the form -mmmnnn, which
requests mmm radial shells around each atom, and a spherical product grid
having nnn θ points and 2*nnn φ points in each shell.
The total number of integration points per atom is therefore 2*mmm*nnn^{2}.
This form is used to specify the (96,32,64) grid commonly cited in benchmark calculations:
Int(Grid=-96032). Note, that any value for nnn is
permitted, although small values are silly (values of nnn < 15 produce
grids of similar size and inferior performance to the special angular grids requested
by the second format above). Large values are expensive. For example, a value
of 200100 would use 2*200*100*100 or 4 million points per atom! RELATIVISTIC
CALCULATIONSDKH Requests a Douglas-Kroll-Hess 2nd order scalar
relativistic calculation [517,518,519,520]
(see [521,522] for
an overview). This method uses a Gaussian nuclear model [523].
DKH2 and DouglasKrollHess are synonyms. NoDKH and
NonRelativistic request a non-relativistic core Hamiltonian, which is the
default. DKH0 Requests a Douglas-Kroll-Hess 0th order scalar
relativistic calculation RESC Requests a RESC scalar relativistic
calculation INTEGRAL FORMAT OPTIONRaff Raff requests
that the Raffenetti format for the two-electron integrals be used. This is the
default. NoRaff demands that the regular integral format be used. It also
suppresses the use of Raffenetti integrals during direct CPHF. This affects conventional
SCF and both conventional and direct frequency calculations. CNDO
Do calculation in main code using CNDO/2 ints. INDO Do calculation
in main code using INDO/2 ints. ZINDO1 Do calculation in main
code using ZINDO/1 ints. ZINDOS Do calculation in main code using
ZINDO/S ints. ALGORITHM SELECTION OPTIONSSSWeights Use
the weighting scheme of Scuseria and Stratmann [524]
for the numerical integration for DFT calculations. This is the default. BWeights
Use the weighting scheme of Becke for numerical integration. NoSComp
Turn off symmetry blocking of MO 2-electron integrals. NoSymmComp is a
synonym for NoSComp.
FMMNAtoms=N
Set the threshhold size for turning on FMM by default to N. The default is 60 atoms. Molecules with symmetry have higher crossover points and the threshold is increased accordingly, to 120 atoms for the C2 and Cs point groups and 240 atoms for higher symmetry.
DPRISM Use the PRISM algorithm [27]
for spdf integral derivatives. This is the default. Rys1E Evaluate
one-electron integrals using the Rys method [525,526,527],
instead of the default method. This is necessary on machines with very limited
memory. Rys2E If writing two-electron integrals, use Rys method
(L314) [192,525,526,527].
This is slower than the default method, but may be needed for small memory machines
and is chosen by default if regular (non-Rafenetti) integrals are requested (by
the NoRaff option). Berny Use Berny sp integral derivative
and second derivative code (L702). Pass Pass specifies
that the integrals be stored in memory via disk, and NoPass disables this.
Synonymous with SCF=[No]Pass, which is the recommended usage. Symm
NoSymm disables and Symm enables the use of symmetry in the evaluation
and storage of integrals (Symm is the default). Synonymous with the keywords
Symm=[No]Int, which is the recommended usage. NoSP Do
not use the special sp integral program (L311) when writing integrals to disk. RevDagSam
Reverse choice of diagonal sampling in Prism. CPKS1Mat Don't
use CPKS multiple-matrices code. SquareLoops Forces square loops.
SqLoops is a synonym for this option. NoJEngine Forbid
use of special Coulomb code. FofCou Use FoFCou even when
it would not otherwise be used. NoFoFCou forbid uses of FoFCou. RevRepFock
Reverse choice of Scat20 vs. replicated Fock matrices.
Schwartz
Turn on Schwartz cutoffs in FMM/NFx. The default is off.
NoMPCut Turn off MP-based
cutoffs in FMM/NFx. NoDFTCut Turn off extra DFT cutoffs. LTrace
Trace Linda transactions. SplitSP Split AO S=P shells into separate
S and P shells. NoSplitSP is the default. SplitSPDF Split
AO S=P=D and S=P=D=F shells into S=P, D, and F. NoSplitSPDF is the default. SplitDBFSP
Split density S=P shells into separate S and P shells. NoSplitDBFSP is
the default. SplitDBFSPDF Split density S=P=D and S=P=D=F into
S=P, D, and F. NoSplitDBFSPDF is the default. NoGather
Forbid use of gather/scatter digestion, even when processing small numbers of
density matrices. Splatter is a synonym for this option. ForceNuc
Do nuclear-electron Coulomb with electron-electron. ECPAcc=N
Set ECP accuracy parameter to N. NoSqrtP Turn off use
of Sqrt(P) in density-based cutoffs. SepJK Do J and K in HF/hybrid
DFT separately for testing. UnconAOBasis Uncontract all the
primitives in the AO basis. UncontractAOBasis is a synonym for this option. UnconDBF
Uncontract all the primitives in the density fitting basis. UncontractDensityBasis
is a synonym for this option.
NoPCXC
Do not precomputed grid information for DFT XC quadrature. NoPreComputeXC
is a synonym for this option. PCXCP Precompute XC quadrature
parameters (number of significant functions, etc.) used for allocation, but do
not store information about individual grid points. PreComputeXCParameters
is a synonym for this option. PCXCWt Precompute XC quadrature
parameters and store weights for each point, to save the work of recalculating
the weights. PreComputeXCWeights is a synonym for this option. PCXCGrid
Precompute XC quadrature parameters and store both the weight and coordinates
for each grid point. PreComputeXCGridPoints is a synonym for this option. Seq2E
Set up for parallel 2 electron integral evaluation but then do not run in parallel
(for debugging). SeqXC Set up for parallel 2 electron integral
evaluation but then do not run in parallel (for debugging). BigAtoms
Make all atom sizes large in XC quadrature. BigShells Make all
shell sizes large in XC quadrature. NoSymAtGrid Do not use (Abelian)
symmetry to reduce grid points on symmetry-unique atoms. LinMIO
Convert to linear storage in FoFCou for testing. RevDistanceMatrix Reverse choice of whether to precompute distance matrix during numerical
quadrature. The default is to precompute for molecules but not for PBC.
NoXCTest
Skip tests of numerical accuracy of XC quadrature.
NoDynParallel
Turn off dynamic work allocation.
INTEGRAL FILE-RELATED
OPTIONSReUse Use an existing integral file. Both the integral
file and checkpoint file must have been preserved from a previous calculation.
Only allowed for single point calculations and Polar=Restart. WriteD2E
Forces the integral derivative file to be written in HF frequency calculations.
Useful only in debugging new derivative code. BUFFER SIZE OPTIONSIntBufSize=N
Sets the integral buffer size to N integer words. The default value (which
is machine-dependant) is generally adequate. D2EBufSize=N
Sets the integral derivative buffer size to N words. SCF |