Pedraza-González L, Charry J, Quintero W, Alí-Torres J, Reyes A. Fast and accurate prediction of proton affinities: revisiting the extended Koopmans' theorem for protons.
Phys Chem Chem Phys 2017;
19:25324-25333. [PMID:
28890980 DOI:
10.1039/c7cp04936f]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work we propose schemes based on the extended Koopmans' theorem for quantum nuclei (eKT), in the framework of the any particle molecular orbital approach (APMO/KT), for the quantitative prediction of gas phase proton affinities (PAs). The performance of these schemes has been tested on a set of 300 organic molecules containing diverse functional groups. The APMO/KT scheme scaled by functional group (APMO/KT-SC-FG) displays an overall mean absolute error of 1.1 kcal mol-1 with respect to experimental data. Its performance in PA calculations is similar to that of post-Hartree-Fock composite methods or that of the APMO second order proton propagator (APMO/PP2) approach. The APMO/KT-SC-FG scheme is also employed to predict PAs of polyfunctional molecules such as the Nerve Agent VX and the 20 common α-amino acids, finding excellent agreement with available theoretical and/or experimental data. The accuracy of the predictions demonstrates that the APMO/KT-SC-FG scheme is a low-cost alternative to adiabatic methods for the calculation of accurate PAs. One of the most appealing features of the APMO/KT-SC-FG scheme, is that PAs can be derived from one single-point APMO Hartree-Fock calculation.
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