Theoretical Chemistry Glossary
25 essential terms — because precise language is the foundation of clear thinking in Theoretical Chemistry.
Showing 25 of 25 terms
Quantum chemical methods derived from first principles without empirical parameters.
A set of mathematical functions used to approximate molecular orbitals in quantum chemical calculations.
A measure of the number of chemical bonds between a pair of atoms, calculated as half the difference between bonding and antibonding electrons.
The separation of nuclear and electronic motions based on the large mass difference between nuclei and electrons.
Complete Active Space Self-Consistent Field method for multiconfigurational systems.
A highly accurate post-Hartree-Fock method using an exponential ansatz to include electron correlation.
A mathematical functional that maps the electron density to the total energy of a quantum system.
In quantum chemistry, the allowed energy values obtained by solving the Schrodinger equation.
The probability of finding an electron at a given point in space, used as the central variable in DFT.
The quantum mechanical energy arising from the antisymmetry requirement of the electronic wavefunction.
A set of classical potential energy functions and parameters used in molecular mechanics and MD simulations.
A bell-shaped mathematical function widely used as basis functions in quantum chemical calculations.
The quantum mechanical operator corresponding to the total energy of a system (kinetic + potential).
A mean-field approximation to the electronic Schrodinger equation using a single Slater determinant.
Two theorems proving that ground-state properties are uniquely determined by the electron density.
A simulation method tracking atomic trajectories by integrating Newton's equations of motion over time.
A mathematical function describing the wave-like behavior of an electron delocalized over an entire molecule.
No two electrons can occupy the same quantum state simultaneously; wavefunctions must be antisymmetric.
A method that treats complex problems as small modifications to simpler, solvable problems.
A multidimensional surface mapping molecular energy as a function of atomic coordinates.
The fundamental equation of quantum mechanics describing how quantum states evolve and determining allowed energy levels.
An iterative procedure where orbitals are optimized until the input and output electron distributions converge.
The highest-energy point along the minimum energy reaction path, corresponding to a saddle point on the PES.
States that any trial wavefunction yields an energy greater than or equal to the true ground-state energy.
A mathematical function (psi) containing all quantum mechanical information about a system; its square gives the probability density.