LEARNING PATHWAY

Density functional theory

Density, Kohn–Sham equations, and approximation.

Learning sequence

1. From density to Kohn–Sham equations — Derive the density variational problem and orthonormal orbital equations.
2. Self-consistency and the total-energy ledger — Follow density mixing and derive the double-counting correction.
3. Exchange–correlation: ingredients and limits — Differentiate LDA/GGA and distinguish fundamental and orbital gaps.

Read in sequence. Each lesson states its assumptions, derivation steps, and domain of validity.