---
title: Theoretical & Computational Chemistry
description: This discipline uses mathematical models, computer simulations, and quantum mechanics to calculate chemical properties and reaction pathways. Learners will understand how to predict molecular behavior, simulate chemical systems, and interpret experimental data using computational tools.
category: sciences
subcategory: chemistry
difficulty: beginner, intermediate, advanced
url: /subject/theoretical-and-computational-chemistry
---

# Theoretical & Computational Chemistry

This discipline uses mathematical models, computer simulations, and quantum mechanics to calculate chemical properties and reaction pathways. Learners will understand how to predict molecular behavior, simulate chemical systems, and interpret experimental data using computational tools.

## Available Resources

5 Websites

## Websites

### 1. Psi4 Quantum Chemistry

Open-source quantum chemistry package with a Python API for Hartree-Fock, DFT, MP2, coupled-cluster, CI and SAPT calculations. Its site hosts documentation, installation instructions and tutorials, so learners can run and script ab initio energy, geometry and property calculations.

**Difficulty:** Beginner | **Price:** Free

**Link:** https://psicode.org/

**Tags:** quantum-chemistry, electronic-structure, ab-initio-methods, density-functional-theory, python

### 2. ORCA Forum

The official user forum for the ORCA quantum chemistry program, run by its developers at the Max Planck Institute for Coal Research. Search it to troubleshoot input files, convergence failures, and method choices in real calculations.

**Difficulty:** Beginner | **Price:** Free

**Link:** https://orcaforum.kofo.mpg.de/

**Tags:** orca, quantum-chemistry, dft, computational-chemistry, forum

### 3. theochem.org

Theochem.org is a resource hub for theoretical and computational chemistry, featuring tutorials, lectures, and reference material on quantum chemistry methods, molecular modeling, and related topics. It also provides links to software tools and practical exercises to apply these methods.

**Difficulty:** Intermediate | **Language:** English | **Price:** Free

**Link:** https://theochem.org

**Tags:** websites, science-research, chemistry

### 4. molssi.org

MolSSI.org is the Molecular Sciences Software Institute, a nonprofit that advances software development for computational chemistry and molecular sciences. The site provides educational resources, tutorials, software standards and best practices, and connections to open-source projects, tools, and internship opportunities for researchers and developers.

**Difficulty:** Intermediate | **Language:** English | **Price:** Free

**Link:** https://molssi.org

**Tags:** websites, science-research, chemistry

### 5. cccbdb.nist.gov

CCCBDB (Computational Chemistry Comparison and Benchmark Database) from NIST is a searchable database of computed gas-phase thermochemistry data for molecules and radicals linked to quantum-chemistry methods. It provides calculated energies, enthalpies of formation, vibrational frequencies and zero-point energies, heat capacities, and benchmark data across various levels of theory and basis sets, with downloadable datasets.

**Difficulty:** Intermediate | **Language:** English | **Price:** Free

**Link:** https://cccbdb.nist.gov

**Tags:** websites, science-research, chemistry

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