In quantum chemistry and computational chemistry, a basis set is a set of functions used to represent the wave function of a molecule or an atom in a quantum mechanical calculation. The basis set consists of a set of mathematical functions, called basis functions, which are combined in a linear combination to approximate the wave function of the system.
The basis set plays a crucial role in quantum mechanical calculations because the exact wave function of a molecule or an atom is typically unknown and cannot be calculated directly. Instead, the wave function is approximated by the linear combination of basis functions, and the coefficients of this linear combination are determined by solving the Schrödinger equation.
There are many different types of basis sets, each with different mathematical properties and levels of accuracy. Some of the most commonly used basis sets include Gaussian basis sets, which use Gaussian functions as basis functions, and plane wave basis sets, which use plane waves as basis functions. Basis sets can also be categorized based on their level of completeness, with larger basis sets providing more accurate results but requiring more computational resources.
The choice of basis set is an important consideration in quantum chemical calculations, as it can have a significant impact on the accuracy and computational cost of the calculation. A carefully chosen basis set can help to ensure that the results of the calculation are accurate and reliable, while a poorly chosen basis set can lead to inaccurate or unreliable results. Know About More Digital Content