Internal density functional theory of molecular systems

摘要

A thermodynamiclike theory of internal equilibrium and constrained equilibrium states of individual molecular systems is formulated, based on the Legendre transformed density functional theory (LT DFT). The molecular system (nonrelativistic, field free, Bornndash;Oppenheimer or nonhyphen;Bornndash;Oppenheimer) is treated as the closed composite thermodynamic system, consisting of very small, rigid (open) subsystems (simple systems) containing a multihyphen;(m)hyphen;component charged fluid in the presence of an external field. The generalized Levy constrained search construction of various lsquo;lsquo;thermodynamicrsquo;rsquo; potentials of LT DFT is given and the local Maxwell relations are derived. The reduction of various secondhyphen;order partial functional derivatives (system sensitivities) in terms of few independent, basic kernels is described, using the Jacobian determinants technique. The qualitative implications for the basic kernels of the theory, from the Maxwell relations and stability criteria (generalized Le Chacirc;telier and Le Chacirc;telierndash;Braun principles) are systematically examined. Finally, possible applications of the general formalism in the thermodynamic analysis of the chemical bond, molecular stability, and chemical reactivity are identified.