MOLPRO

14 INTEGRATION 89
DMP2
THR DMP2
THREST DMP2
THRINT DMP2
THRPROD DMP2
Selects the transformation method for direct MP2:
DMP2=−1: automatic selection, depending on the available
memory.
DMP2=0: use fully direct method for DMP2 (min. two integral
evaluations, possibly multipassing, no disk space).
DMP2=1: use semi-direct method for DMP2 (one to four integral
evaluations, depending on PAGE DTRAF).
DMP2=2: use DKEXT to compute exchange operators in DMP2
(one integral evaluation). This is only useful in local DMP2 calculations
with many distant pairs.
General threshold for generation of 2-external integrals in DMP2.
If given, this is used as a default for all DMP2 thresholds described
below.
Prescreening threshold for generation of 2-external integrals.
Defaults: [THR DMP2, THREST DTRAF, THR DTRAF, THREST,
default].
Integral threshold for generation of 2-external integrals.
Defaults: [THR DMP2, THRINT DTRAF, THR DTRAF, THRINT,
default].
Product threshold for generation of 2-external integrals
Defaults: [THR DMP2, THRPROD DTRAF, THR DTRAF, THRPROD,
default].
Specific options for direct local MP2 (LMP2):
DTRAF
Selects the transformation method for direct LMP2:
DTRAF ≥ 0: generates the 2-external integrals (exchange operators)
first in AO basis and transforms these thereafter in a
second step to the projected, local basis. The disk storage requirements
hence scale cubically with molecular size.
DTRAF = −1: generates the 2-external integrals (exchange operators)
directly in projected basis. The disk storage requirements
hence scale linearly with molecular size. This (together
with PAGE DTRAF = 0) is the recommended algorithm for very
large molecules (cf. linear scaling LMP2, chapter 29).
DTRAF = −2: alternative algorithm to generate the exchange
operators directly in projected basis. Usually, this algorithm
turns out to be computationally more expensive than the one
selected with DTRAF = −1. Note, that neither DTRAF = −1
nor DTRAF = −2 work in the context of LMP2 gradients.
THR LMP2
THREST LMP2
THRQ1 LMP2
General threshold for generation of 2-external integrals in linear
scaling LMP2. If given, this is used as a default for all
LMP2 thresholds described below.
Prescreening threshold for generation of 2-external integrals.
Defaults: [THR LMP2, THREST DTRAF, THR DTRAF, THREST,
default].
Threshold used in the first quarter transformation.
Defaults: [THR LMP2, THRPROD DTRAF, THR DTRAF, THRPROD,
default].