Editing Computational chemistry (section)

=== Density functional methods ===
{{Main article|Density functional theory}}
Density functional theory (DFT) methods are often considered to be ''[[ab initio quantum chemistry methods|ab initio methods]]'' for determining the molecular electronic structure, even though many of the most common [[Functional (mathematics)|functionals]] use parameters derived from empirical data, or from more complex calculations. In DFT, the total energy is expressed in terms of the total one-[[electronic density|electron density]] rather than the wave function. In this type of calculation, there is an approximate [[Hamiltonian (quantum mechanics)|Hamiltonian]] and an approximate expression for the total electron density. DFT methods can be very accurate for little computational cost. Some methods combine the density functional exchange functional with the Hartree–Fock exchange term and are termed [[hybrid functional]] methods.<ref>{{Cite journal |last1=De Proft |first1=Frank |last2=Geerlings |first2=Paul |last3=Heidar-Zadeh |first3=Farnaz |last4=Ayers |first4=Paul W. |date=2024-01-01 |title=Conceptual Density Functional Theory |url=https://www.sciencedirect.com/science/article/abs/pii/B9780128219782000258 |journal=Comprehensive Computational Chemistry |language=en-US |pages=306–321 |doi=10.1016/B978-0-12-821978-2.00025-8 |isbn=978-0-12-823256-9}}</ref>