The “XSAPT” method, which may be regarded either as an acronym for
“XPol+SAPT” or for “extended” symmetry adapted perturbation theory (SAPT),
was originally introduced by Jacobson and Herbert,
602
J. Chem. Phys.
(2011),
134,
pp. 094118.
Link
,
539
Phys. Chem. Chem. Phys.
(2012),
14,
pp. 7679.
Link
and later by Lao and Herbert,
737
J. Phys. Chem. Lett.
(2012),
3,
pp. 3241.
Link
,
738
J. Chem. Phys.
(2013),
139,
pp. 034107.
Link
,
740
J. Phys. Chem. A
(2015),
119,
pp. 235.
Link
,
742
J. Chem. Theory Comput.
(2018),
14,
pp. 2955.
Link
,
743
J. Chem. Theory Comput.
(2018),
14,
pp. 5128.
Link
as a low-scaling, systematically-improvable method for intermolecular interactions that
could be applicable to large systems. The idea was
to replace the need for empirical parameters in the XPol method with
on-the-fly evaluation of exchange-repulsion and dispersion interactions via
pairwise-additive SAPT. Stated differently, XSAPT uses XPol to evaluate many-body
(non-pairwise-additive) polarization effects, but then assumes that dispersion
and exchange-repulsion interactions are pairwise additive, and
evaluates them via pairwise SAPT0 or SAPT0(KS) calculations.
The method was significantly extended by Lao, Herbert, and
co-workers,
737
J. Phys. Chem. Lett.
(2012),
3,
pp. 3241.
Link
,
738
J. Chem. Phys.
(2013),
139,
pp. 034107.
Link
,
740
J. Phys. Chem. A
(2015),
119,
pp. 235.
Link
,
742
J. Chem. Theory Comput.
(2018),
14,
pp. 2955.
Link
,
743
J. Chem. Theory Comput.
(2018),
14,
pp. 5128.
Link
,
193
J. Phys. Chem. Lett.
(2019),
10,
pp. 2706.
Link
,
817
J. Chem. Phys.
(2019),
151,
pp. 031102.
Link
,
460
J. Chem. Phys.
(2021),
155,
pp. 034103.
Link
with various approximations applied in place of the SAPT0 or SAPT0(KS) dispersion terms,
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Acc. Chem. Res.
(2021),
54,
pp. 3679.
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which are both the least accurate and most expensive contributions to second-order SAPT.
A concise overview of XSAPT-based methods can be found in Ref.
192
Acc. Chem. Res.
(2021),
54,
pp. 3679.
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and a comprehensive review in Ref.
.
In particular, the XSAPT+MBD method
193
J. Phys. Chem. Lett.
(2019),
10,
pp. 2706.
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stands out as a way to obtain qualitative insight
about noncovalent interactions in large systems, backed by quantitative energetics calculations.
192
Acc. Chem. Res.
(2021),
54,
pp. 3679.
Link
In many cases, this type of analysis has upended textbook “conventional wisdom".
549
J. Phys. Chem. A
(2021),
125,
pp. 7125.
Link