Analytical method for the representation of atoms‐in‐molecules densities

Abstract

We present analytic refinements and applications of the deformed atomic densities method [Fernández Rico, J.; López, R.; Ramírez, G. J Chem Phys 1999, 110, 4213-4220]. In this method the molecular electron density is partitioned into atomic contributions, using a minimal deformation criterion for every two-center distributions, and the atomic contributions are expanded in spherical harmonics times radial factors. Recurrence relations are introduced for the partition of the two-center distributions, and the final radial factors are expressed in terms of exponential functions multiplied by polynomials. Algorithms for the practical implementation are developed and tested, showing excellent performances. The usefulness of the present approach is illustrated by examining its ability to describe the deformation of atoms in different molecular environments and the relationship between these atomic densities and some chemical properties of molecules.

Rapid topography mapping of scalar fields: Large molecular clusters

“…Such a method was also used by Hansen and Coppens 24 for computing electrostatic potential and its derivatives. Later, Rico and López et al [18][19][20][21][22] proposed an efficient DAM procedure for evaluation of molecular scalar fields such as MED and MESP by partitioning into atomic contributions. However, the difference between the DAM and Coppens-Hansen method comes from two sources: the way in which the density is partitioned into pseudoatomic fragments and the functions chosen for representing the radial factors.…”

“…The performance of the method for evaluation of MED and MESP has been tested out on many systems such as water, nitrobenzene, etc. 20,21 This DAM method of evaluating the MED and MESP has been implemented in the package DAMQT. 22 The advantage of this method is that the calculation of function and its derivatives is very rapid and is dependent only on the expansion parameter l max .…”

“…35 Considering this, the topography code is applied to map the MED and MESP CP's of a cluster containing 20 Lithium atoms at MP2/6-31+G(d) level of theory. The MED and MESP CP's of (Li) 20 are displayed in Figure 2. For this cluster system, 10 non-nuclear maxima are found in MED.…”

“…17 This previously proposed algorithm is improved upon in the present work and coupled with the deformed atoms in molecules (DAM) method [18][19][20][21][22] which permits rapid, yet sufficiently accurate, evaluation of MED and MESP. The newly developed automated code is applied to large cluster systems viz.…”

Fragment-Localized Kohn−Sham Orbitals via a Singles Configuration-Interaction Procedure and Application to Local Properties and Intermolecular Energy Decomposition Analysis

“…This decomposition scheme, based on orbitals rather than on the density, is extensively studied for instance by Fernández Rico et al 47,48 3.3. Local Properties As Dipole Moments.…”