Quantum chemistry

Quantum chemistry applies quantum mechanics to atoms and molecules to explain their structures, bonds, properties, and reactions.

Schrödinger equation: A wave equation that determines how a quantum state changes and which energies a system can have. Molecular calculations begin by describing electrons and nuclei through quantum states.
Molecular orbital: A wavefunction describing an electron distributed across a molecule, usually with a characteristic energy. Molecular orbitals express how atomic states combine into bonding and antibonding states.
Computational chemistry: The use of computer-based models to study chemical systems and predict their behavior. Quantum chemistry provides its electronic-structure methods, alongside classical and statistical approaches.
Quantum mechanics: The physical theory describing matter and energy at atomic and subatomic scales. Quantum chemistry applies this broader theory to chemical systems.
Semi-empirical quantum chemistry: Quantum-chemical methods that simplify calculations using parameters fitted to experimental or higher-level data. It reduces computational effort by replacing some explicit quantum-mechanical integrals with fitted approximations.
Born–Oppenheimer approximation: An approximation that separates electronic and nuclear motion because nuclei are much heavier than electrons. It makes molecular electronic structure calculations tractable by treating nuclei as fixed.
Electron correlation: The coordinated motion of electrons beyond the independent-particle approximation. Accurately representing correlated electrons is a central challenge in molecular calculations.
Molecular spectroscopy: The study of how molecules absorb, emit, or scatter electromagnetic radiation. Calculated energy levels and transition probabilities help assign molecular spectra.
Walter Heitler: A German physicist whose work with Fritz London applied quantum mechanics to the hydrogen molecule. Their calculation became an early quantum-mechanical account of a chemical bond.
Molecular mechanics: A classical modeling approach that represents molecules with atoms, bonds, and parameterized energy functions. Unlike quantum chemistry, it generally does not model electronic structure explicitly.

Linked from 25 pages