caa a22 4500 605488592 CHVBK 20210128100456.0 cr unu---uuuuu 210128e20151101xx s 000 0 eng 10.1007/s00214-015-1743-2 doi (NATIONALLICENCE)springer-10.1007/s00214-015-1743-2 Bochicchio Roberto Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA (CONICET), Ciudad Universitaria, 1428, Buenos Aires, Argentina aut On the non-integer number of particles in molecular system domains: treatment and description [Elektronische Daten] [Roberto Bochicchio] The energy of an atomic or molecular system undergoing Coulomb interactions is well known at the integer numbers of its neutral or ionic configurations. Nevertheless, the physical domains (atoms in molecules) inside the whole molecular system possess a non-integer number of particles due to the electron exchange with its surrounding. Hence, the dependence of the energy, the density matrix and their marginal distributions (reduced density matrices) with the number of particles become a problem of fundamental importance in the description of the electron distribution, its properties and transformations. In this work, we present a rigorous mathematical and physical basis for the treatment of this problem within the grand-canonical statistical distribution of few particles. In this context, the derivatives of the energy and the density referred as chemical descriptors (especially chemical potential and hardness) are analyzed in both cases, when the system is isolated and when it is subject to the interaction with an environment. The ground state energy convexity dependence with the number of particles of these systems simplifies the description. Springer-Verlag Berlin Heidelberg, 2015 Grand-canonical ensemble nationallicence Electronic structure nationallicence Density matrix nationallicence Descriptors nationallicence Theoretical Chemistry Accounts Springer Berlin Heidelberg 134/11(2015-11-01), 1-9 1432-881X 134:11<1 2015 134 214 https://doi.org/10.1007/s00214-015-1743-2 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00214-015-1743-2 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Bochicchio Roberto Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA (CONICET), Ciudad Universitaria, 1428, Buenos Aires, Argentina aut NATIONALLICENCE 773 0- Theoretical Chemistry Accounts Springer Berlin Heidelberg 134/11(2015-11-01), 1-9 1432-881X 134:11<1 2015 134 214