Recent developments in QM/MM methods towards open-boundary multi-scale simulations

Abstract

Combined quantum mechanics/molecular mechanics (QM/MM) methods have been widely used in multi-scale modelling and simulations of physical, chemical and biological processes in complex environments. In this review, we provide an overview of the recently developed QM/MM algorithms, with emphasis on our works, towards the ultimate goal of establishing an open boundary between the QM and MM subsystems. The open boundary is characterised by on-the-fly exchanges of partial charges and atoms between the QM and MM subsystems, allowing us to focus on the small QM subsystem of primary interest in dynamics simulations. An open-boundary scheme has the promise to the utilisations of small QM subsystems, high-levels of QM theory and long simulation times, which can potentially lead to new insights.

Keywords::

• partial charge transfer
• adaptive partition
• electronegativity equalisation
• conservation of energy and momentum
• on-the-fly reclassification

Acknowledgements

This work is supported by the National Science Foundation (CHE0952337). This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by the National Science Foundation grant number CHE-130090.We thank Jingzhi Pu for critical reading of the manuscript and insightful comments.

Disclosure statement

The authors declare no competing financial interest.