Remarks on Mayer's Reduced Density Matrix Method

Part I Reduced Density Matrix Functional Theory

Some remarks on modularity density

A “quantitative function” for community detection called modularity density has been proposed by Li, Zhang, Wang, Zhang, and Chen in [Phys. Rev. E 77, 036109 (2008)]. We study the modularity density maximization problem and we discuss some features of the optimal solution. More precisely, we show that in the optimal solution there can be communities having negative modularity density, and we pr...

The time-dependent two-particle reduced density matrix method: LiH in strong laser fields

Comment on “ Density - matrix renormalization - group method for excited states ”

In a recent paper (Phys. Rev. B 59, 9699 (1999)), Chandross and Hicks claim to present a new density matrix renormalisation group (DMRG) method for dealing with excited states of quantum lattice models. The proposed improvement to the DMRG—the inclusion of excited state wave functions in addition to the ground state in the density matrix when calculating excitations— is in fact standard pratice...

Some Remarks on the Mass Density Distribution

The distribution of the density of mass in several simple model systems is analyzed. In particular, the relation between the localization of a particle and its mass is studied in detail. The dependence of the function describing mass density distribution on the choice of the reference point and, in this context, the process of emerging the molecular shape as a function of masses of the constitu...