What is density functional theory (DFT)?

Density functional theory (DFT) is a quantum mechanical method for computing the electronic structure and total energy of materials from first principles — meaning it uses only the laws of quantum mechanics and the atomic numbers of the elements, without empirical fitting parameters.

How It Works

DFT maps the many-electron problem onto an effective single-electron problem by using the electron density as the fundamental variable (rather than the many-body wavefunction). The Kohn-Sham equations are solved self-consistently to find the ground-state electron density and total energy.

What DFT Can Predict

• Crystal structure and lattice parameters
• Formation energies and thermodynamic stability
• Electronic band structure and band gaps
• Elastic constants and mechanical properties
• Phonon spectra and thermal properties
• Magnetic ordering and moments

Limitations

• Band gaps are underestimated by standard functionals (GGA/PBE) by 30-50%
• Strongly correlated systems (f-electron materials, Mott insulators) are poorly described
• Van der Waals interactions require special functionals
• Calculations are performed at 0 K and may miss temperature-dependent effects