Subject: BSSE and (H2O)2

From: [email-masked]
Date: Mon, 06 Jul 1998 12:58:27 -0700

Over the past several weeks there have been several messages posted to the
CCL concerning basis set superposition error and the water dimer.  Here is
an admittedly selective list of just some of the calculations dealing with
the water dimer.  This system has been examined by a large number of
researchers.
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Water Dimer Interaction Energies (kcal/mol)

  Basis              Method      DeltaE          CP     Reference
aug-cc-pVQZ          MP2(FC)     -5.05           N   D. Feller, JCP 96, 6104
                     MP2(FC)     -4.81           Y   (1992). (See Note 1)
Est. CBS             MP2(FC)     -4.95 +/- 0.05  NA

                     R12-MP2     -4.94           NA  W. Klopper, et al. JCP,
                                                     103, 1085 (1995).

aug-cc-pV5Z          MP2(FC)     -4.98           N   M.W. Feyereisen et al. JPC
Est. CBS             MP2(FC)     -4.9  +/- 0.1   NA  100, 2993 (1996).
Est. CBS             MP2         -4.95 +/- 0.1   NA
Est. CBS             FCI         -5.0  +/- 0.1   NA  (see Note 2)

20s15p11d9f7g4h2i1k  MP2(FC)     -4.92           N   M. Schutz et al. JCP, 107,
                     MP2(FC)     -4.88           Y   4597 (1997).
Est. CBS             MP2         -4.94 +/- 0.02  NA  (see Note 3)

aug-cc-pV5Z          MP2(FC)     -4.98           N   A. Halkier, et al. TCA,
97,
daug-cc-pVQZ         MP2(FC)     -5.10           N   150 (1997).
                     MP2(FC)     -4.81           Y
Est. CBS             MP2(FC)     -4.91 +/- 0.07  NA
aug-cc-pVQZ          CCSD(T)(FC) -5.05           N
Est. CBS             CCSD(T)(FC) -4.96 +/- 0.07  NA

CP: N=No, Y=Yes/ NA=Not Applicable
Note 1: The aug-cc-pVQZ binding energy was estimated by assuming the
        contributions of the diffuse f and g functions on oxygen were
        additive.
Note 2: The full CI estimate includes the effects of geometry relaxation,
        core/valence corrections and higher order correlation recovery.
Note 3: The (20s15p11d9f7g4h2i1k) oxygen basis set of Schutz et al. was
        uncontracted.  It was used with an 11s5p4d3f2g1h hydrogen basis
        set for a total of 1046 functions in the water dimer. These authors
        state that their core/valence correction was only 0.04 kcal/mol,
        whereas they claim that Feyereisen et al. recommended a value of
        0.09 kcal/mol.  But in the abstract to the work of Feyereisen et al.
        they clearly state that CV effects increase the binding energy by
        ~0.05 kcal/mol.

-- 

David Feller                                | Mail Stop K1-96
Environmental Molecular Sciences Laboratory | 906 Battelle Blvd
Battelle Pacific Northwest National Lab     | Richland, WA 99352
                                            | 
e-mail:[email-masked]                  | Fax: (509)-375-6631