DP is a free software package for physicists implementing ab initio linear-response TDDFT (time-dependent density functional theory) in frequency-reciprocal space and on a plane wave basis set. It allows to calculate both dielectric spectra, such as EELS (electron energy-loss spectroscopy), IXSS (inelastic X-ray scattering spectroscopy) and CIXS (coherent inelastic X-ray scattering spectroscopy), and also optical spectra, e.g. optical absorption, reflectivity, refraction index. The systems range from periodic/crystalline solids, to surfaces, clusters, molecules and atoms made of insulators, semiconductors and metal elements. It implements the RPA (random phase approximation), the TDLDA or ALDA (adiabatic local-density approximation) plus other non-local approximations, including or neglecting local-field effects. It is distributed under the scientific software open-source academic for free license.
- Runge, Erich; Gross, E. K. U. (19 March 1984). "Density-Functional Theory for Time-Dependent Systems". Physical Review Letters. American Physical Society (APS). 52 (12): 997–1000. Bibcode:1984PhRvL..52..997R. doi:10.1103/physrevlett.52.997. ISSN 0031-9007.
- Gross, E. K. U.; Kohn, Walter (23 December 1985). "Local density-functional theory of frequency-dependent linear response". Physical Review Letters. American Physical Society (APS). 55 (26): 2850–2852. Bibcode:1985PhRvL..55.2850G. doi:10.1103/physrevlett.55.2850. ISSN 0031-9007. PMID 10032255.