Contributions of pauli repulsions to the energetics and physical properties computed in QM/MM methods

Journal Article

Conventional combined quantum mechanical/molecular mechanical (QM/MM) methods lack explicit treatment of Pauli repulsions between the quantum-mechanical and molecular-mechanical subsystems. Instead, classical Lennard-Jones (LJ) potentials between QM and MM nuclei are used to model electronic Pauli repulsion and long-range London dispersion, despite the fact that the latter two are inherently of quantum nature. Use of the simple LJ potential in QM/MM methods can reproduce minimal geometries and energies of many molecular clusters reasonably well, as compared to full QM calculations. However, we show here that the LJ potential cannot correctly describe subtle details of the electron density of the QM subsystem because of the neglect of Pauli repulsions between the QM and MM subsystems. The inaccurate electron density subsequently affects the calculation of electronic and magnetic properties of the QM subsystem. To explicitly consider Pauli interactions with QM/MM methods, we propose a method to use empirical effective potentials on the MM atoms. The test case of the binding energy and magnetic properties of a water dimer shows promising results for the general application of effective potentials to mimic Pauli repulsions in QM/MM calculations. © 2013 Wiley Periodicals, Inc.

Full Text

Duke Authors

Cited Authors

  • Jin, Y; Johnson, ER; Hu, X; Yang, W; Hu, H

Published Date

  • 2013

Published In

PubMed ID

  • 23922165

International Standard Serial Number (ISSN)

  • 0192-8651

Digital Object Identifier (DOI)

  • 10.1002/jcc.23401