# Pauli Exclusion Principle

**Formula:**`Pauli Exclusion Principle`

## Introduction to Pauli Exclusion Principle

The Pauli exclusion principle is a fundamental principle in quantum mechanics that states that no two identical fermions (particles with half-integer spin) can occupy the same quantum state simultaneously. Mathematically, this principle is often represented by a function that returns 0 if the quantum states of the two particles are the same, and 1 if they are different. In this formula, ** occupancyA** and

**represent the occupancy numbers of two fermions in a given quantum state. The result is 0 if both occupancies are 1, and 1 otherwise.**

*occupancyB*## Parameter usage:

`occupancyA`

= occupancy number of the first fermion`occupancyB`

= occupancy number of the second fermion

## Output:

`result`

= 0 if both occupancies are 1, 1 otherwise

## Data validation

The occupancy numbers should be between 0 and 2.

## Summary

The Pauli exclusion principle has important implications in understanding the behavior of electrons in atomic, molecular, and solid-state systems.