26 research outputs found
The MC-QTAIM: A framework for extending the atoms in molecules analysis beyond purely electronic systems
The quantum theory of atoms in molecules, QTAIM, is employed to identify AIM
and quantify their interactions through the partitioning of molecule into
atomic basins in the real space and it is confined only to the purely
electronic systems composed of electrons as quantum particles and the nuclei as
clamped point charges. The extended version of the QTAIM, called the
multi-component QTAIM, MC-QTAIM, bypasses this border and makes it possible to
identify AIM and quantify their interactions in systems composed of multiple
quantum particles that electrons may or may not be one of their components
opening a new door for the analysis of the exotic AIM and bonds. In this
contribution, two conjectures, called Bader conjecture, BC, and extended Bader
conjecture, EBC, are proposed as the cornerstones of the real-space
partitioning of a molecule into atomic basins within the context of the QTAIM
and the MC-QTAIM, respectively. A literature survey on various few-body quantum
systems composed of quarks, nucleons, and elementary particles like muons and
positrons is also done unraveling the fact that in all these diverse systems
there are unambiguous cases of clusterizations. These clustered systems,
irrespective to their components, behave as if they are molecules composed of
some kind of atoms, instead of being an amorphous mixture of quantum particles.
In the case of the muonic and the positronic molecules computational studies
reveal that the AIM structures of these systems are well-captured by the EBC.
Beyond identifying atomic basins, both QTAIM and MC-QTAIM attribute properties
to AIM, which is their share from the molecular expectation values of quantum
observables. It is demonstrated that not only the share from the average value
of an observable may be attributed to an atomic basin, but also the fluctuation
of each basin property is also quantifiable.Comment: This is a polished version of v2 draf