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We present an implementation of alchemical free energy simulations at the quantum mechanical level by directly interpolating the electronic Hamiltonian. The method is compatible with any level of electronic structure theory and requires…

Chemical Physics · Physics 2024-09-02 Chenghan Li , Xing Zhang , Garnet Kin-Lic Chan

In this paper, a variational perturbation scheme for nonrelativistic many-Fermion systems is generalized to a Bosonic system. By calculating the free energy of an anharmonic oscillator model, we investigated this variational expansion…

Quantum Physics · Physics 2009-11-06 Wen-Fa Lu , Sang Koo You , Jino Bak , Chul Koo Kim , Kyun Nahm

Although machine-learning potentials have recently had substantial impact on molecular simulations, the construction of a robust training set can still become a limiting factor, especially due to the requirement of a reference ab initio…

Chemical Physics · Physics 2023-03-29 Krystof Brezina , Hubert Beck , Ondrej Marsalek

Thermodynamic integration (TI) offers a rigorous method for estimating free-energy differences by integrating over a sequence of interpolating conformational ensembles. However, TI calculations are computationally expensive and typically…

Statistical Mechanics · Physics 2024-12-04 Bálint Máté , François Fleuret , Tristan Bereau

The Alchemical Transfer Method (ATM) is herein validated against the relative binding free energies of a diverse set of protein-ligand complexes. We employed a streamlined setup workflow, a bespoke force field, and the AToM-OpenMM software…

Chemical Physics · Physics 2023-08-21 Lieyang Chen , Yujie Wu , Chuanjie Wu , Ana Silveira , Woody Sherman , Huafeng Xu , Emilio Gallicchio

We present a machine-learning approach, based on normalizing flows, for modelling atomic solids. Our model transforms an analytically tractable base distribution into the target solid without requiring ground-truth samples for training. We…

We present a novel technique for learning the mass matrices in samplers obtained from discretized dynamics that preserve some energy function. Existing adaptive samplers use Riemannian preconditioning techniques, where the mass matrices are…

Machine Learning · Computer Science 2017-11-08 Anirban Roychowdhury , Srinivasan Parthasarathy

The free energy of the Random Energy Model at the transition point between ferromagnetic and spin glass phases is calculated. At this point, equivalent to the decoding error threshold in optimal codes, free energy has finite size…

Statistical Mechanics · Physics 2009-11-10 David B. Saakian

We discuss different free energies for materials in static electric and magnetic fields. We explain what the corresponding Hamiltonians are, and describe which choice gives rise to which result for the free energy change, dF, in the…

Statistical Mechanics · Physics 2009-11-10 Onuttom Narayan , A. P. Young

A candidate application for quantum computers is to simulate the low-temperature properties of quantum systems. For this task, there is a well-studied quantum algorithm that performs quantum phase estimation on an initial trial state that…

Quantum Physics · Physics 2024-11-04 Chi-Fang , Chen , Alexander M. Dalzell , Mario Berta , Fernando G. S. L. Brandão , Joel A. Tropp

Systems with many interacting stochastic constituents are fully characterized by their free energy. Computing this quantity is therefore the objective of various approaches, notably perturbative expansions, which are applied in problems…

Statistical Mechanics · Physics 2026-04-08 Tobias Kühn

Sampling equilibrium distributions is fundamental to statistical mechanics. While flow matching has emerged as scalable state-of-the-art paradigm for generative modeling, its potential for equilibrium sampling in condensed-phase systems…

Computational Physics · Physics 2026-03-31 Emil Hoffmann , Maximilian Schebek , Leon Klein , Frank Noé , Jutta Rogal

We develop a computational method to learn a molecular Hamiltonian matrix from matrix-valued time series of the electron density. As we demonstrate for three small molecules, the resulting Hamiltonians can be used for electron density…

Computational Physics · Physics 2020-09-01 Harish S. Bhat , Karnamohit Ranka , Christine M. Isborn

Measuring the expectation value of the molecular electronic Hamiltonian is one of the challenging parts of the variational quantum eigensolver. A widely used strategy is to express the Hamiltonian as a sum of measurable fragments using…

Quantum Physics · Physics 2023-01-04 Seonghoon Choi , Ignacio Loaiza , Artur F. Izmaylov

We carry out highly accurate \emph{ab initio} path integral Monte Carlo (PIMC) simulations to directly estimate the free energy of various warm dense matter systems including the uniform electron gas and hydrogen without any nodal…

Quantum Gases · Physics 2024-07-02 Tobias Dornheim , Zhandos Moldabekov , Sebastian Schwalbe , Jan Vorberger

The proposed method of the free energy calculation is based on the approximation of the energy distribution in the microcanonical ensemble by the Gaussian distribution. We hope that our approach will be effective for the systems with…

Disordered Systems and Neural Networks · Physics 2015-06-23 Boris Kryzhanovsky , Leonid Litinskii

We develop a theoretical model for calibrating the absorption imaging of cold atoms under high magnetic fields. Comparing to zero or low magnetic fields, the efficiency of the absorption imaging becomes lower while it requires an additional…

Atomic Physics · Physics 2023-07-20 Yuqi Liu , Zhongchi Zhang , Shiwan Miao , Zihan Zhao , Huaichuan Wang , Wenlan Chen , Jiazhong Hu

Taking advantage of the advances in generative deep learning, particularly normalizing flow, a framework, called Boltzmann Generator, has recently been proposed for the purpose of generating equilibrium atomic configurations from the…

Statistical Mechanics · Physics 2022-07-27 Rasool Ahmad , Wei Cai

Retrosynthesis -- the process of identifying a set of reactants to synthesize a target molecule -- is of vital importance to material design and drug discovery. Existing machine learning approaches based on language models and graph neural…

Chemical Physics · Physics 2021-12-10 Ruoxi Sun , Hanjun Dai , Li Li , Steven Kearnes , Bo Dai

We review uses of the generalized-ensemble algorithms for free-energy calculations in protein folding. Two of the well-known methods are multicanonical algorithm and replica-exchange method; the latter is also referred to as parallel…

Statistical Mechanics · Physics 2007-05-23 Y. Sugita , Y. Okamoto