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Issue 37, 2017
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Fast and accurate prediction of proton affinities: revisiting the extended Koopmans' theorem for protons

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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.

Graphical abstract: Fast and accurate prediction of proton affinities: revisiting the extended Koopmans' theorem for protons

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Publication details

The article was received on 21 Jul 2017, accepted on 04 Sep 2017 and first published on 04 Sep 2017


Article type: Paper
DOI: 10.1039/C7CP04936F
Citation: Phys. Chem. Chem. Phys., 2017,19, 25324-25333
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    Fast and accurate prediction of proton affinities: revisiting the extended Koopmans' theorem for protons

    L. Pedraza-González, J. Charry, W. Quintero, J. Alí-Torres and A. Reyes, Phys. Chem. Chem. Phys., 2017, 19, 25324
    DOI: 10.1039/C7CP04936F

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