Time-dependent density functional theory

<p>Time-dependent density-functional theory (TDDFT) is a <a href="/facts/Quantum_mechanical/BRc3Mzgr">quantum mechanical</a> theory used in physics and chemistry to investigate the properties and <a href="/facts/Molecular_dynamics/yR3DNt6U">dynamics</a> of many-body systems in the presence of time-dependent potentials, such as <a href="/facts/Electric_field/tt4MooBs">electric</a> or <a href="/facts/Magnetic_field/Ta8Ev588">magnetic fields</a>. The effect of such fields on molecules and solids can be studied with TDDFT to extract features like <a href="/facts/Electron_excitation/66pkjfmB">excitation energies</a>, frequency-dependent response properties, and <a href="/facts/Absorption_spectroscopy/GH7RC14D">photoabsorption spectra</a>.
</p><p>TDDFT is an extension of <a href="/facts/Density-functional_theory/wwz4Gqdg">density-functional theory</a> (DFT), and the conceptual and computational foundations are analogous – to show that the (time-dependent) <a href="/facts/Wave_function/KgM5ykjY">wave function</a> is equivalent to the (time-dependent) <a href="/facts/Electronic_density/L5yDsk6j">electronic density</a>, and then to derive the effective potential of a fictitious non-interacting system which returns the same density as any given interacting system. The issue of constructing such a system is more complex for TDDFT, most notably because the time-dependent effective potential at any given instant depends on the value of the density at all previous times. Consequently, the development of time-dependent approximations for the implementation of TDDFT is behind that of DFT, with applications routinely ignoring this memory requirement.
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Time-dependent density functional theory open-in-new

Time-dependent density functional theory