Finite-temperature many-body perturbation theory in the grand canonical ensemble

振动频率与斯托克效应调谐率：基于连续电化学模型和大配额密度泛函理论

Vibrational frequencies and stark tuning rate with continuum electro-chemical models and grand canonical density functional theory

本文基于连续电化学模型和大配额密度泛函理论，研究了振动频率和斯托克效应调谐率在不同集合条件下的差异。

Finite-temperature many-body perturbation theory for electrons: Algebraic recursive definitions, second-quantized derivation, linked-diagram theorem, general-order algorithms, grand canonical and canonical ensembles

A comprehensive and detailed account is presented for the finite-temperature many-body perturbation theory for electrons that expands in power series all thermodynamic functions on an equal footing. Algebraic recursions in the style of the Rayleigh-Schrödinger perturbation theory are derived for the grand potential, chemical potential, internal energy, and entropy in the grand canonical ensemble and for the Helmholtz energy, internal energy, and entropy in the canonical ensemble, leading to their sum-over-states analytical formulas at any arbitrary order. For the grand canonical ensemble, thes…

Grand Canonical Adaptive Resolution Simulation for Molecules with Electrons: A Theoretical Framework based on Physical Consistency

A theoretical scheme for the treatment of an open molecular system with electrons and nuclei is proposed. The idea is based on the Grand Canonical description of a quantum region embedded in a classical reservoir of molecules. Electronic properties of the quantum region are calculated at constant electronic chemical potential equal to that of the corresponding (large) bulk system treated at full quantum level. Instead, the exchange of molecules between the quantum region and the classical environment occurs at the chemical potential of the macroscopic thermodynamic conditions. T he Grand Canon…

Grand canonical electronic density-functional theory: algorithms and applications to electrochemistry

First-principles calculations combining density-functional theory and continuum solvation models enable realistic theoretical modeling and design of electrochemical systems. When a reaction proceeds in such systems, the number of electrons in the portion of the system treated quantum mechanically changes continuously, with a balancing charge appearing in the continuum electrolyte. A grand-canonical ensemble of electrons at a chemical potential set by the electrode potential is therefore the ideal description of such systems that directly mimics the experimental condition. We present two distin…

Grand-Canonical Adaptive Resolution Centroid Molecular Dynamics: Implementation and Application

We have implemented the Centroid Molecular Dynamics scheme (CMD) into the Grand Canonical-like version of the Adaptive Resolution Simulation Molecular Dynamics (GC-AdResS) method. We have tested the implementation on two different systems, liquid parahydrogen at extreme thermodynamic conditions and liquid water at ambient conditions; the reproduction of structural as well as dynamical results of reference systems are highly satisfactory. The capability of performing GC-AdResS CMD simulations allows for the treatment of a system characterized by some quantum features and open boundaries. This l…

Probing Spatial Locality in Ionic Liquids with the Grand Canonical Adaptive Resolution Molecular Dynamics Technique

We employ the Grand Canonical Adaptive Resolution Molecular Dynamics Technique (GC-AdResS) to test the spatial locality of the 1-ethyl 3-methyl imidazolium chloride liquid. In GC-AdResS atomistic details are kept only in an open sub-region of the system while the environment is treated at coarse-grained level, thus if spatial quantities calculated in such a sub-region agree with the equivalent quantities calculated in a full atomistic simulation then the atomistic degrees of freedom outside the sub-region play a negligible role. The size of the sub-region fixes the degree of spatial locality o…

巨正则与正则势能面的理论研究：带电界面处电子响应与几何响应的相互作用

A Theoretical Investigation of the Grand- and the Canonical Potential Energy Surface: The Interplay between Electronic and Geometric Response at Electrified Interfaces

本研究通过严格数学推导，分析了带电界面在巨正则与正则系综下的势能面驻点响应特性，揭示了两种系综电容特性的差异及成因，为电化学界面的从头算模拟提供了理论支撑。

Path Integral Molecular Dynamics within the Grand Canonical-like Adaptive Resolution Technique: Simulation of Liquid Water

Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however computationally this technique is very demanding. The abovementioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One possible solution to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolutio…

Molecular Dynamics in a Grand Ensemble: Bergmann-Lebowitz model and Adaptive Resolution Simulation

This article deals with the molecular dynamics simulation of open systems that can exchange energy and matter with a reservoir; the physics of the reservoir and its interactions with the system are described by the model introduced by Bergmann and Lebowitz.Despite its conceptual appeal, the model did not gain popularity in the field of molecular simulation and, as a consequence, did not play a role in the development of open system molecular simulation techniques, even though it can provide the conceptual legitimation of simulation techniques that mimic open systems. We shall demonstrate that …

量子蒙特卡洛模拟中存在费米子符号问题时计算巨正则系综期望值的重加权方案

Reweighting scheme for the calculation of grand-canonical expectation values in quantum Monte Carlo simulations with a fermion sign problem

针对量子蒙特卡洛模拟中费米子符号问题导致的巨正则系综计算瓶颈，本文提出一种重加权方案，通过正则系综下费米子区最大有效粒子数的模拟保留巨正则期望值计算，并以温稠密电子气为例验证其应用价值。

由混合4D非平衡MD/MC方法驱动的巨正则分子动力学模拟：在LAMMPS中的实现及在电解质溶液中的应用

Grand-canonical molecular dynamics simulations powered by a hybrid 4D nonequilibrium MD/MC method: Implementation in LAMMPS and applications to electrolyte solutions

本研究将一种混合4D非平衡MD/MC巨正则模拟方法在LAMMPS中实现并配套Python接口，经电解质体系验证，可大幅提升离子交换模拟效率。

Schwarzites for Natural Gas Storage: A Grand-Canonical Monte Carlo Study

The 3D porous carbon-based structures called Schwarzites have been recently a subject of renewed interest due to the possibility of being synthesized in the near future. These structures exhibit negatively curvature topologies with tuneable porous sizes and shapes, which make them natural candidates for applications such as CO2 capture, gas storage and separation. Nevertheless, the adsorption properties of these materials have not been fully investigated. Following this motivation, we have carried out Grand-Canonical Monte Carlo simulations to study the adsorption of small molecules such as CO…

巨正则重加权分子动力学模拟表明RNA结构探测实验中存在协同效应

Molecular dynamics simulations with grand-canonical reweighting suggest cooperativity effects in RNA structure probing experiments

本研究使用全原子分子动力学模拟，在巨正则系综下开发了一种计算分子亲和力的通用技术，揭示了RNA与SHAPE试剂结合时的协同效应会导致浓度依赖性反应性，并通过新实验进行了定性验证。