The four equations of quantum mechanics are introduced as follows:

1. Schrodinger equation Schrodinger equation is the most basic equation in quantum mechanics, which describes the motion state of particles under the action of external force, specifically, it is an equation describing the properties of waves. Schrodinger equation can give a wave function to describe the position and state of a particle at any time in space, and the modulus of the wave function represents the probability distribution of finding a particle at a certain position.

2. Heisenberg equation Heisenberg equation is the basis of matrix mechanics, which puts forward a new theory to describe particle interaction which is different from wave equation. Heisenberg equation describes the change of particle state by describing the measurement results, that is, compared with Schrodinger equation, it pays more attention to particle measurement and observation.

Dirac equation Dirac equation describes the motion of rotating particles. The equation combines relativity and quantum mechanics and has a special mathematical structure. It is the methodological basis of quantum field theory in the field of high-energy physics, and it is also widely used, such as playing an important role in quark, antiquark and meson analysis theory and experimental verification.

4. Pauli equation Pauli equation is called the "second basic equation" of electron spin in quantum mechanics. It describes the motion state of spin particles in electromagnetic field, and solves the problem that when the energy is very small, it can not be described by classical mechanical concepts.

These four equations are all important theories in quantum mechanics. By studying these equations, we have a deeper understanding of the nature and structure of the micro-world. At the same time, due to the application of these equations, our research in physical chemistry, material science, information science and other fields has also been greatly developed.