CCL: AW: BSSE in transition states

 Sent to CCL by: Kai Leonhard [kai.leonhard-,-ltt.rwth-aachen.de]
 Dear all,
 The application of CPC to TSs seems to be quite controversial to me. There are
 other Papers that claim
 that applying the CPC to TSs is better than not doing so (or even the only
 acceptable way).
 E.g. Kobko and Dannenberg claim that
 'Clearly, CP-corrected surfaces lead to noticeable improvements
 in the geometrically optimized TSs obtained with
 relatively small basis sets. The geometries and associated
 activation energies become closer to those obtained with larger
 basis sets. The CP corrections to these parameters tend to
 diminish as the basis sets are improved. These observations may
 be contrasted with the earlier suggestion by Lendvay and Mayer
 that CP correction is inappropriate for the optimizations of TSs.[18]
 They quite correctly noted that certain choices for the fragments
 used in the CP correction calculation would be inappropriate.
 In particular, they criticized two applications of CP to TSs.[21]
 For example, had we used two fragments (CH4 and CH3*) for
 the methane/methyl H-transfer reaction, we would have obtained
 an inappropriate, unsymmetrical TS. However, a flexible choice
 of the fragments will usually allow reasonable CP calculations
 of the TS, at least for cases where all fragments are neutral.
 Nevertheless, the seemingly arbitrary nature of the fragment
 choices bear some detailed discussion.'
 My impression is that maybe Lendvay and Mayer wrote their paper mainly to
 motivate their CHA method because they state that CPC is not perfect and that
 a better method is desirable. This is true, but applying CPC seems better to me
 than
 completely ignoring BSSE.
 More recently, it was discussed by Richard et al. that intramolecular BSSE
 is even relevant for stable molecules. They suggest a 3:1 weighted average of
 CPC and non-cpc results as best energy estimates (for cluster interactions,
 though).
 My question is now whether the debate can be considered resolved now or it is
 still an ongoing discussion. Any thoughts or experiences on CPC for TSs are
 highly appreciated.
 Best regards,
 Kai
 Prof. Dr. Kai Leonhard
 Juniorprofessor for Model-Based Fuel Design
 Room 215
 Schinkelstraße 8
 D-52056 Aachen
 Phone:  +49 (0)241 80 - 98174
 Fax:        +49 (0)241 80 - 92255
 E-Mail: kai.leonhard|-|ltt.rwth-aachen.de
 Kobko, N. & Dannenberg, J. J.
 Effect of basis set superposition error (BSSE) upon ab initio calculations of
 organic transition states
 J. Phys. Chem. A, {2001}, {105}, {1944-1950}
 Richard, R. M.; Lao, K. U. & Herbert, J. M.
 Approaching the Complete-Basis Limit with a Truncated Many-Body Expansion
 J. Chem. Phys., 2013, 139, 224102
 -----Ursprüngliche Nachricht-----
 Von: owner-chemistry+leonhard==ltt.rwth-aachen.de|-|ccl.net [mailto:owner-chemistry+leonhard==ltt.rwth-aachen.de|-|ccl.net] Im Auftrag
 von Florent LOUIS florent.louis(-)univ-lille1.fr
 Gesendet: Mittwoch, 11. Dezember 2013 18:11
 An: Kai Leonhard
 Betreff: CCL: BSSE in transition states
 Sent to CCL by: "Florent  LOUIS" [florent.louis~~univ-lille1.fr] Dear
 John,
 The BSSE correction with the counterpoise method is applicable to weakly
 interacting molecular complexes but not to TS, where it can lead to
 discontinuous potential surfaces (see paper from Lendvay and Mayer, Some
 Difficulties in Computing BSSE Corrected Potential Surfaces of Chemical
 Reactions. Chem. Phys. Lett.1998, 297 (56), 365373) Therefore, the CP correction
 can be just viewed as an estimate of the error bars for reaction barriers.
 Best regards,
 Florent
 > "John Simmie john.simmie]_[nuigalway.ie"  wrote:
 >
 > Sent to CCL by: "John  Simmie" [john.simmie .. nuigalway.ie] I
 have
 > recently seen quite large BSSE corrections of ca 20 kJ/mol claimed for
 > a TS (C, H, O only) for coupled cluster calculations with basis set
 > aug-cc-pVDZ for zero-point corrected electronic energy barriers of ca
 > 90 kJ/mol The correction decreases to ca 10 kJ/mol with aug-cc-pVTZ
 >
 > is this well-known and/or documented somewhere please?
 >
 > John M. Simmie//NUI Galway//Irelandhttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt