Understanding Quantum Chemistry from H2MODEL

Introduction

It is not straightforward for beginners in quantum chemistry to understand how to obtain numerical results from abstract theoretical formulae. Therefore I wrote this small tutorial during 2009 to 2012, discussing in detail on how to carry out an actual Hartree-Fock, configuration interaction, coupled-cluster, time-dependent/independent density functional theory, geometry optimization or Hessian calculation using H₂ as example. It therefore was also known as "Understanding Quantum Chemistry from H2MODEL" several years ago.

Understanding Quantum Chemistry from H2MODEL: Document
Program binary: Windows; Linux
Program source code: Codes

Contents

1 Model Description
2 Molecular Integral Computation
3 Single Configuration RHF Computation
3.1 Practical RHF Computation
3.2 Electronic States
3.3 Molecular Orbitals
3.4 Electron Density
3.5 Component Analysis of Wave Function
3.6 The Dissociation Limit of RHF Wave Function
3.7 The Stability of RHF
4 CI Computation: Naive Approach
4.1 Practical Computation
4.2 Dissociation Limit
4.3 Component Analysis
4.4 Correlation Effects
4.5 Population Analysis
5 Adiabatic States and Noncrossing Principle
6 CI Computation: GUGA Approach
6.1 Shavitt Graph
6.2 Davidson Diagonization
7 Perturbation Method: MP2
7.1 Perturbation Expansion of Accurate Energy
7.2 Convergency
8 Coupled Cluster Computation
8.1 Practical Computation
8.2 Relationship between FCI and CC
9 Optimization and Frequency Analysis of PES
9.1 RHF PES Analysis
9.2 General PES Analysis
10 Ground State DFT Computation
10.1 Energy Calculation
10.2 Self-interaction and Fractional Occupation Number Error
10.3 Asymptotic Error and Hirao Correction
11 Time-dependent DFT computation
11.1 Practical Computation
11.2 Comparing With Direct SCF
11.3 Triplet Instability and Imaginary Excitaion Energy
12 GAMESS and H2MODEL "Manual"
12.1 Checking by GAMESS
12.2 H2MODEL "Manual"