Computational Methods in Chemistry

The material on Computational Methods in Chemistry discusses various theoretical approaches used to model molecular structures, energies, and properties, ranging from molecular mechanics to quantum mechanics. Molecular mechanics (MM) treats molecules as collections of atoms interacting through force fields, where the total energy consists of bond stretching, angle bending, torsional, and non-bonded interaction terms, making it highly efficient for large systems such as proteins. Semiempirical quantum mechanical methods simplify the Schrödinger equation by introducing empirical parameters to reduce computational cost, making them suitable for preliminary studies of medium-sized molecules. *Ab initio* methods solve the Schrödinger equation from first principles without empirical parameters, providing high accuracy but at a significant computational expense, particularly in Hartree–Fock approaches and with the use of extensive basis sets. Density Functional Theory (DFT), on the other hand, replaces the many-electron wavefunction with electron density, offering an optimal balance between accuracy and computational efficiency, especially through exchange–correlation functionals such as LDA, GGA, and hybrid functionals like B3LYP. Overall, each computational method has distinct strengths and limitations, and its selection must be tailored to the system size, research objective, and required level of accuracy.