10.1021/acs.jpca.6b01043.s001
Oriana Brea
Oriana
Brea
Muammar El Khatib
Muammar El
Khatib
Gian Luigi Bendazzoli
Gian Luigi
Bendazzoli
Stefano Evangelisti
Stefano
Evangelisti
Thierry Leininger
Thierry
Leininger
Celestino Angeli
Celestino
Angeli
The Spin-Partitioned Total-Position Spread Tensor:
An Application To Diatomic Molecules
American Chemical Society
2016
moment cumulant
SP
configuration interaction
molecule charge mobility
covalent bonds
tensor
Λ αα
Λ αβ
FCI
delocalization
TPS
energy curve
position operator
SS
partition
multireference character
wave function
Diatomic Molecules
2016-03-25 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/The_Spin_Partitioned_Total_Position_Spread_Tensor_An_Application_To_Diatomic_Molecules/3205087
The
spin partition (SP) of the total-position spread (TPS) tensor
is applied to the case of a few light diatomic molecules at full configuration
interaction (FCI) level. It appears that the SP-TPS tensor gives informations
that are complementary with respect to the corresponding spin-summed
(SS) quantity. The spin-summed total position-spread tensor (SS-TPS,
Λ) is defined as the second moment cumulant of the total position
operator, and the SP-TPS is its partition in equal (<b>Λ</b><sub><i>αα</i>+<i>ββ</i></sub>) and different spin (<b>Λ</b><sub><i>αβ</i>+<i>βα</i></sub>) contributions. Then, the
SS-TPS allows description of the molecule charge mobility, while the
SP-TPS allows description of the spin delocalization. The most relevant
Cartesian-component for both tensors (SS-TPS and SP-TPS) is the component
along the chemical bond (Λ<sup>∥</sup>), and it was found
that its behavior was related to the type of interaction involved.
For covalent bonds the SP-TPS has a squared growth when the bond is
stretched, while for ionic bonds there exists a faster-than-linear
growth after the avoided-crossing between the covalent and the ionic
states. Other exotic bonds, like He<sub>2</sub> and Be<sub>2</sub>, were also considered, and a particular spin delocalization was
able to describe the different character of the two weakly bonded
molecules, and specially the multireference character of the wave
function along the dissociative potential energy curve.