Ab initio

Ab initio is a Latin term meaning "from the beginning". In various fields, it is used to describe methods or approaches that are based on basic principles or theories, without relying on empirical data or previous knowledge.

Definition

The term ab initio is derived from Latin, where it literally means "from the beginning". It is used in several contexts, including law, physics, and computational chemistry, to denote methods or approaches that start from basic principles or theories, without relying on empirical data or previous knowledge.

Use in Law

In law, ab initio refers to something that has been in effect from the start. For example, if a contract is void ab initio, it is considered invalid from the outset, as if it had never existed. This term is often used in contract law and property law.

Use in Physics

In physics, ab initio methods are used in the field of quantum mechanics to solve the Schrödinger equation from first principles. These methods, which include Hartree-Fock and Density Functional Theory, do not rely on empirical data or approximations, but instead use the fundamental laws of physics to calculate properties of systems.

Use in Computational Chemistry

In computational chemistry, ab initio methods are used to predict the structures and properties of molecules. These methods, which include Gaussian and Møller-Plesset perturbation theory, use the principles of quantum mechanics to calculate the electronic structure of molecules from scratch, without relying on empirical data or approximations.

See Also

• Hartree-Fock
• Density Functional Theory
• Gaussian (software)
• Møller-Plesset perturbation theory