Jian Liu

Born November 1, 1978 in Jiangxi, China.

Boya Distinguished Professor, College of Chemistry and Molecular Engineering, Peking University

Email:jianliupku@pku.edu.cn
Web: external link

American Chemical Society Physical Chemistry Division Outstanding Postdoctoral Research Award (2012); Chinese National "Thousand Young Talents Program" scholarship (2012); Chinese Chemical Society Tang Au-Qing Young Investigator Award in Theoretical Chemistry (2015); Pople Medal of Asia-Pacific Association of Theoretical and Computational Chemists (2019); Outstanding Young Scientist Award of National Natural Science Foundation of China (2022); Minzhu Scholar Prize, Peking University (2023); Member of the Scientific Board of Asia-Pacific Association of Theoretical and Computational Chemists (2025); Member of International Academy of Quantum Molecular Science (2025)

Author of:

Important Contributions:

• Generalized Coordinate-Momentum Phase Space Representations of Quantum Mechanics for Composite Systems: Liu proposed a generic framework to construct rigorous representations on constraint coordinate-momentum phase space (CPS) for pure finite-state systems, whose mathematical structure is diffeomorphic to the complex Stiefel manifolds. By establishing constraint phase space for discrete degrees of freedom (DOFs) and employing infinite phase space for continuous DOFs, he developed the exact generalized coordinate-momentum formulation for composite systems in chemistry, physics, and quantum information. It lays the solid foundation of developing consistent trajectory-based nonadiabatic dynamics methods.
• Trajectory-based Quantum Dynamics Approaches:
  1. Born-Oppenheimer phase space quantum dynamics methods. Liu formulated a novel theoretical framework termed “equilibrium continuity dynamics” (ECD). ECD is the zeroth order approximation in an exact series expansion of the quantum phase space propagator, which leads to practical trajectory-based Born-Oppenheimer quantum dynamics methods. The framework conserves the quantum Boltzmann distribution and recovers exact thermal correlation functions (even of nonlinear operators) in both the classical and harmonic limits. Liu pioneered the first practical quantum dynamics method satisfying these two critical fundamental criteria, namely, path integral Liouville dynamics (PILD), which was derived from the elaborate combination of imaginary-time path integral and the ECD framework.
  2. Nonadiabatic field approach. Liu proposed nonadiabatic field (NaF), a conceptually novel approach for nonadiabatic quantum dynamics with independent trajectories on generalized quantum coordinate-momentum phase space. He was the first to demonstrate the significance of the nonadiabatic nuclear force arising from the nonadiabatic coupling between different electronic states.
• Path Integral Molecular Dynamics Methods: Liu employed the phase space evolution operator to develop a unified framework that includes both stochastic and deterministic thermostatting algorithms and covers various Monte Carlo or molecular dynamics barostatting algorithms. The framework enabled the rational design of a novel “middle” scheme for path integral molecular dynamics methods. It significantly enhances the sampling efficiency and accuracy for canonical ensembles and isobaric-isothermal ensembles where nuclear quantum effects are important.
• His methodologies furnish versatile and effective tools for unraveling quantum mechanical effects in thermodynamic properties (densities, heat capacities, isothermal compressibilities, thermal expansion coefficients, free energies, etc.) and dynamic observables (carrier mobilities, reaction/relaxation rates, vibrational/electronic spectra, etc.) in real complex systems within gas-phase, condensed-phase, or interfacial environments.