Perturbation theory

• Barker and Henderson perturbation theory
• Discrete perturbation theory
• Free energy perturbation method (FEP)
• McQuarrie and Katz perturbation theory
• Rowlinson perturbation theory
• SAFT (Statistical Associating Fluid Theory)
  • PC-SAFT
  • GC-SAFT
  • Soft-SAFT
  • SAFT-$\gamma$
  • iSAFT
  • SAFT-VR
  • SAFT-VRE
• Song and Mason perturbation theory
• Weeks-Chandler-Anderson perturbation theory
• Wertheim's first order thermodynamic perturbation theory (TPT1)
• Wertheim's second order thermodynamic perturbation theory (TPT2)
• Zhou's third-order thermodynamic perturbation theory
• Zwanzig's first order perturbation theory

Recommended reading

• Jean-Pierre Hansen and I.R. McDonald "Theory of Simple Liquids" (Third Edition) Chapter 5: "Perturbation theory"