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Application of the Mermin entropy principle to the “apparatus” density functional theory
Author(s) -
Tachibana Akitomo
Publication year - 1989
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560350302
Subject(s) - density functional theory , density matrix , entropy (arrow of time) , excited state , functional theory , orbital free density functional theory , physics , quantum mechanics , principle of maximum entropy , operator (biology) , chemistry , time dependent density functional theory , mathematics , quantum , biochemistry , statistics , repressor , transcription factor , gene
An “apparatus” operator approach is presented for the extension of the density functional theory of Hohenberg, Kohn, and Mermin. Using the Mermin entropy principle, a one‐to‐one correspondence is established between the density matrix for the system and the electron charge density for a finite‐temperature system in the presence of an apparatus. In the zero‐temperature limit in the absence of an apparatus, the Hohenberg–Kohn theory is recovered. The central aspect of this new density functional theory is that the principle of maximum entropy is applied to the system plus its surroundings under the additional constraint that the electron charge density is given. The system is treated as a subsystem of a composite system and is not necessarily in the equilibrium state as in the Mermin theory. As an example, it is shown how, in principle, excited states are encompassed by the theory.