MOLPRO

29 LOCAL CORRELATION TREATMENTS 211
LOCSING=locsing
MAXANG=lmax
PIPEKAO=option
NONORM=value
LMP2ALGO=value
OLDDEF=value
Thresholds:
THRPIP=thresh
THRORB=thresh
THRLOC=thresh
THRMP2=thresh
jiterm=-2: Enable a variation of the asymmetric domain formalism:
Exchange operators will initially be projected to the asymmetric domain
instead of simply packed.
If locsing.ne.0, the single excitations use the full space, i.e., they are
not treated locally. This is only works for LOCAL=1.
The purpose of this experimental option is to reduce the basis set
sensitivity of the Boughton-Pulay (BP) method for domain selection.
Only basis functions with angular momentum up to lmax-1 are included
when computing the overlap of the approximate and exact orbitals.
For example, MAXANG=2 means to omit all contributions of
d, f and higher angular momentum functions. To obtain reasonable
domains, the value of THRBP must often be reduced (to 0.97 or so).
This option should only be used with care!
If option≥ 0, the orbitals are localized my maximizing the coefficients
of basis functions of a given type at a given atom. Normally, this is
only useful to uniquely define degenerate orbitals in atoms. For instance,
when this option is used to localize the orbitals for a dimer
like (Ar) 2 at a very long distance, clean s, p x , p y , and p z atomic orbitals
will be obtained. It is not recommended to use this option for
molecular calculations!
Determines if projected functions are normalized (not recommended).
value=-1: projected orbitals are normalized before redundancy check.
value=0: projected orbitals are normalized after redundancy check
(default).
value=1: projected orbitals are normalized in redundancy check, afterwards
unnormalized.
value=2: projected orbitals are never normalized (default in gradient
calculations).
If nonzero, use low-order scaling method in LMP2 iterations. Values
can be 1, 2, or 3, and 3 is usually fastest if large basis sets are used.
For compatibility with older versions: if nonzero, revert to old defaults.
Options set before this may be overwritten.
Threshold for Pipek-Mezey localization. The localization is assumed
to be converged if all 2×2 rotation angles are smaller then thresh. The
default is 1.d −12. It can also be modified globally using GTHRESH,
LOCALI=thresh.
Threshold for eliminating functions from pair domains whose norm
is smaller then thresh after projecting out the occupied space. The
default is throrb=1.d-6.
Threshold for eliminating redundant basis functions from pair domains.
For each eigenvalue of ˜S i j < thresh one function is deleted.
The default is 1.d-6. The method used for deleting functions depends
on the parameters IDLEIG and IBASO.
Threshold for neglecting small fock matrix couplings in the LMP2
iterations (default 1.d-8). Specifying a larger threshold speeds up the
iterations but may lead to small errors in the energy. In the initial
iterations, a larger threshold is chosen automatically. It is gradually
reduced to the specified final value during the iterations.