skip to main content

SciTech ConnectSciTech Connect

Title: The total position-spread tensor: Spin partition

The Total Position Spread (TPS) tensor, defined as the second moment cumulant of the position operator, is a key quantity to describe the mobility of electrons in a molecule or an extended system. In the present investigation, the partition of the TPS tensor according to spin variables is derived and discussed. It is shown that, while the spin-summed TPS gives information on charge mobility, the spin-partitioned TPS tensor becomes a powerful tool that provides information about spin fluctuations. The case of the hydrogen molecule is treated, both analytically, by using a 1s Slater-type orbital, and numerically, at Full Configuration Interaction (FCI) level with a V6Z basis set. It is found that, for very large inter-nuclear distances, the partitioned tensor growths quadratically with the distance in some of the low-lying electronic states. This fact is related to the presence of entanglement in the wave function. Non-dimerized open chains described by a model Hubbard Hamiltonian and linear hydrogen chains H{sub n} (n ≥ 2), composed of equally spaced atoms, are also studied at FCI level. The hydrogen systems show the presence of marked maxima for the spin-summed TPS (corresponding to a high charge mobility) when the inter-nuclear distance is about 2 bohrs.more » This fact can be associated to the presence of a Mott transition occurring in this region. The spin-partitioned TPS tensor, on the other hand, has a quadratical growth at long distances, a fact that corresponds to the high spin mobility in a magnetic system.« less
Authors:
; ;  [1] ;  [1] ;  [2] ;  [3] ;  [4]
  1. Laboratoire de Chimie et Physique Quantiques - LCPQ/IRSAMC, Université de Toulouse (UPS) et CNRS (UMR-5626), 118, Route de Narbonne, 31062 Toulouse Cedex (France)
  2. (Spain)
  3. Institut für Chemie und Biochemie - Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany)
  4. Dipartimento di Chimica Industriale “Toso Montanari”, Università di Bologna, Viale Risorgimento 4, I–40136 Bologna (Italy)
Publication Date:
OSTI Identifier:
22416209
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMS; CONFIGURATION INTERACTION; DISTANCE; ELECTRONS; FLUCTUATIONS; HAMILTONIANS; HYDROGEN; MOBILITY; MOLECULES; PARTITION; POSITION OPERATORS; QUANTUM ENTANGLEMENT; SPIN; TENSORS; WAVE FUNCTIONS