A self-consistent Coulomb bath model is presented to provide an accurate and efficient way of performing calculations for interfragment electrostatic and polarization interactions. In this method, a condensed-phase system is partitioned into molecular fragment blocks. Each fragment is embedded in the Coulomb bath due to other fragments. Importantly, the present Coulomb bath is represented using a density fitting method in which the electron densities of molecular fragments are fitted using an atom-centered auxiliary basis set of Gaussian type. The Coulomb bath is incorporated into an effective Hamiltonian for each fragment, with which the electron density is optimized through an iterative double self-consistent field (DSCF) procedure to realize the mutual many-body polarization effects. In this work, the accuracy of interfragment interaction energies enumerated using the Coulomb bath is tested, showing a good agreement with the exact results from an energy decomposition analysis. The qualitative features of many-body polarization effects are visualized by electron density difference plots. It is also shown that the present DSCF method can yield fast and robust convergence with near-linear scaling in performance with increase in system size.
Bibliographical noteFunding Information:
Ministry of Science and Technology of the People's Republic of China, Grant/Award Number: 2017YFB0203400; National Natural Science Foundation of China, Grant/Award Numbers: 21873036, 91541124 Funding information
This work was supported in part by the Ministry of Science and Technology (Grant Number 2017YFB0203400) and the National Natural Science Foundation of China (Grant Numbers 21873036 and 91541124). The authors also thank Dr Yunwen Tao for valuable discussion and suggestion about computational details.
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- coulomb bath mode
- density fitting
- fragment-based method