Orbital representation of kinetic energy pressure

Abstract

The kinetic energy pressure (KEP) is quantified in terms of displaced charges and their orbital representations. Two deformation density matrices are introduced to separate reorganization of the electron density due to Pauli antisymmetrization from that of orbital relaxation. The formalism is applied to interaction of carbon nanotubes with hydrogen molecule and the results confirmed that KEP has the main contribution to such interaction. Also, it was found that the contribution of KEP can be easily traced in the complex formation.

Nature of closed‐ and open‐shell interactions between noble metals and rare gas atoms

“…Suppose that the electron densities of complex and isolated Au and Rg atoms are represented by ρ Au−Rg , ρ Au , and ρ Rg , respectively, and the total deformation density due to complex formation can be written as Δρ total = ρ Au−Rg −(ρ Au + ρ Rg ). On the other hand, Δρ total can be decomposed into Δρ Pauli and Δρ relax , which stand for the steric repulsion between the fragments originated from antisymmetrization of the two fragments' electrons and charge density relaxation originated from interfragment attraction (repulsion), respectively …”

“…Table displays Δρ total and its two components using a graphical representation and the corresponding number for Au–Rg and Au +/– –Rg complexes where the excess charge on the Au atom in its isolated state is considered for calculation of ρ Au . In the depicted isosurfaces, blue (darker) and pink (lighter) colors stand for the area in which charge density is appeared and disappeared, respectively, while the numbers manifests the number of displaced electron for the corresponding Δρ …”

“…Deformation density analysis is also accomplished for Au containing species. Total deformation density (Δρ) is defined as the difference between electron density due to supramolecule and those of individual fragments: The total deformation density can be decomposed into Pauli repulsion and relaxation components . According to this decomposition scheme, the electronic density reorganization during the supramolecule formation originates from two essential steps: (1) electron density reorganization due to the Pauli repulsion (Δρ relax ), and (2) relaxation of electron density in the supramolecule environment (Δρ Pauli ).…”

“…According to this decomposition scheme, the electronic density reorganization during the supramolecule formation originates from two essential steps: (1) electron density reorganization due to the Pauli repulsion (Δρ relax ), and (2) relaxation of electron density in the supramolecule environment (Δρ Pauli ). To quantify the displaced charge in each step, the corresponding density matrix can be diagonalized and summation over positive eigenvalues reflects the number of displaced electrons …”

Resonance structures might correspond to excited states in polycyclic conjugated systems

“…System I is one ring of a small CNT in diameter which is claimed to be the smallest diameter CNT [14]. The interaction of hydrogen molecule with such small CNT is recently analyzed by the present author, theoretically [15]. The resonance structures of the CNTs are displayed in Table 1.…”