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B3LYP

Michael Tynes

B3LYP is a hybrid exchange-correlation functional (xc) used in density functional theory (DFT). In DFT, a quantum mechanical many-electron system is modeled by the Kohn-Sham (KS) equations which depend on functional of single-electron density that captures energy associated with electron exchange and correlation. If this xc functional were known exactly, then solving the KS equations would exactly solve the Schrodinger equation for a ground-state system. The exact xc functional cannot be known …

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Basis Set Superposition Error

Chuh-Chuan Huang

Basis set superposition error (BSSE) is an overestimation issue on the interaction energy. One main interest of quantum chemistry calculations is to understand interaction, such as non-covalent interaction between two or more atoms or molecules.

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Bond Dissociation Energy

Di Chen

Bond dissociation energy (BDE) quantifies the energetic cost of breaking a chemical bond and separating a molecule into two fragments at infinite separation. In quantum chemistry, it is defined as the difference between the total electronic energy of a molecule at its equilibrium geometry and the sum of the electronic energies of the resulting fragments in their ground electronic states.

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Born-Oppenheimer Approximation

Whitney Short

The Born-Oppenheimer Approximation (BOA) is the approximation that electronic motion can be separated from nuclear motion, yielding a wavefunction that is the product of electronic and nuclear wavefunctions. This approximation is possible because in many cases, nuclei move much, much more slowly than electrons and accelerate much less than them, largely because they are much heavier than electrons.

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