Solvent Models

Deciphering the Role of Solvent in Molecular Properties and Reactions

The solvent environment plays an essential role in chemical processes, including catalysis, photochemical reactions, and the stability of materials. Recent years, new experimental techniques have been introduced to characterize liquid-phase reactions. This places an urgent need for efficient computational models to further predict the effect of solvents on the rate and product distribution. I aim at developing methods and protocols for efficient modeling of reactions in realistic experimental conditions.

I developed the graphical processing units (GPUs) algorithms to accelerate the widely used implicit solvent model, the conductor-like polarizable continuum model (C-PCM) With 10X-100X speed-ups for ground-state Hartree Fock (HF) or density functional theory (DFT) calculation, my algorithm keeps the world’s fastest record. More importantly, these award-winning method developments enable more realistic simulation of large biomolecular systems in solution phase: the bulk solvent effects can now be simulated with little computational overhead.

Related Publications

F. Liu, N. Luehr, H. J. Kulik, and T. J. Martínez. “Quantum chemistry for solvated molecules on graphical processing units using polarizable continuum models.” Journal of chemical theory and computation 11 (2015): 3131-3144.

B. D. Mar., H. W. Qi, F. Liu, and H. J. Kulik. “Ab Initio screening approach for the discovery of lignin polymer breaking pathways.” The Journal of Physical Chemistry A 119 (2015): 6551-6562.

Solvent effects for excited state properties and photophysical processes

The significances of solvent effects also lie in the simulation of spectroscopy and photochemistry, which involves evaluation of excited-state properties. To this end, time-dependent density functional theory (TDDFT) has been increasingly employed in recent years due to its superior computational scalability. To study the excited-state properties of solvated molecules, I implemented the TDDFT algorithm in the C-PCM solvent model with GPU acceleration, with 40-150X speed-ups. The implementation includes both the equilibrium and non-equilibrium solvation schemes that can describe fluorescence and vertical excitations, respectively. This method enables PCM-TDDFT for systems with ca. 1000 atoms, making the excited-state simulation in combined implicit/explicit solvent model practical.

Related Publications

F Liu, D. M. Sanchez, H J. Kulik, and T. J. Martínez. “Exploiting graphical processing units to enable quantum chemistry calculation of large solvated molecules with conductor-like polarizable continuum models.” International Journal of Quantum Chemistry 119 (2019): e25760

Impacts of solvent models on the electronic structure

The conductor-like polarizable continuum model (CPCM), although initially introduced as an implicit solvent model, was reported to improve SCF convergence in some large molecules. However, the underlying mechanisms and applicable use cases were unclear. We investigated the impacts of CPCM on the SCF convergence and density delocalization error of DFT calculations and revealed the mechanism for CPCM’s impacts on the electronic structure.

Related Publications

Fangning Ren, Fang Liu*, “Impacts of Polarizable Continuum Models on the SCF Convergence and DFT Delocalization Error of Large Molecules”, J. Chem. Phys. (2022, just accepted)