Overview

Molecular dynamics (MD) simulation is a computational technique that models the time-dependent behavior of atoms and molecules by numerically integrating Newton’s equations of motion. Each atom is treated as a point mass subject to forces derived from a molecular mechanics force field — a mathematical function describing bonded interactions (bonds, angles, dihedrals) and non-bonded interactions (van der Waals and electrostatic). By following atomic trajectories over nanoseconds to microseconds, MD simulations reveal conformational changes, ligand binding events, and folding pathways that are difficult to observe experimentally.

Methods

A typical MD workflow begins with system preparation: solvating the biomolecule in a water box, adding ions to neutralize charge, and energy-minimizing to remove steric clashes. The system is then equilibrated under constant temperature and pressure before the production run generates trajectories for analysis. Enhanced sampling techniques — such as replica exchange, metadynamics, and steered MD — overcome the timescale limitations of conventional MD. Parallel computing on GPUs enables simulations of large systems such as ribosomes and membrane proteins.

Applications

MD simulations provide atomistic insight into protein folding and chaperones by capturing folding intermediates and the role of chaperone machinery. They complement experimental protein structure determination by adding a dynamic dimension to static structures. In drug discovery, MD predicts binding kinetics and residence times, and it is used to study ligand-induced conformational changes. Simulations also connect to chemical thermodynamics by computing free energy differences through methods like thermodynamic integration and free energy perturbation.