# Computational chemistry methods based on MNDO and tools for improving their accuracy

## TL;DR

This paper reviews the history and development of computational chemistry methods based on the MNDO approximation and provides tools to improve their accuracy.

## Contribution

The paper provides a detailed summary of MNDO-based methods and supporting files to aid future developments.

## Key findings

- MNDO-based methods have evolved significantly since 1977, with forms like AM1 and PM3.
- Supporting material is provided to help in the development of future computational methods.

## Abstract

Semiempirical computational methods based on the MNDO approximation have a long history. Since its release in 1977, the original MNDO method has evolved steadily, passing through several forms (AM1, PM3, etc.) up to the present. Each new form represented an improvement, and it is anticipated that the evolution will continue for many more years.

A summary of the history of MNDO-based methods will be given, followed by a description of the mechanisms involved in developing some of the current methods. To assist in this, a set of files illustrating the steps and procedures involved is provided in Supporting Material; hopefully these will be useful in facilitating the development of future methods.

The online version contains supplementary material available at 10.1007/s00894-026-06653-3.