The two-component quantum theory of atoms in molecules (TC-QTAIM): foundations

Shahbazian

2019

ChemPhysChem

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Recently it has been proposed that the positron, the anti‐particle analog of the electron, is capable of forming an anti‐matter bond in a composite system consists of two hydride anions and a positron [Angew. Chem. Int. Ed. 57, 8859–8864 (2018)]. In order to dig into the nature of this novel bond the newly developed multi‐component quantum theory of atoms in molecules (MC‐QTAIM) is applied to this positronic system. The topological analysis reveals that this species is composed of two atoms in molecules, each containing a proton and half of the electronic and the positronic populations. Further analysis elucidates that the electron exchange phenomenon is virtually non‐existent between the two atoms and no electronic covalent bond is conceivable in between. On the other hand, it is demonstrated that the positron density enclosed in each atom is capable of stabilizing interactions with the electron density of the neighboring atom. This electrostatic interaction suffices to make the whole system bonded against all dissociation channels. Thus, the positron indeed acts like an anti‐matter glue between the two atoms.

Section: Resultsmentioning

confidence: 99%

On the Nature of the Positronic Bond

Shahbazian

2019

ChemPhysChem

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“…The inquiry of atomic charges of Mu‐N1‐A, Mu‐N3‐A, and Mu‐N7‐G reveals a nontrivial isotope‐induced charge re‐organization while the atomic charge/spin densities of the attached Mu/H and the addition sites do not display any significant isotope sensitivity. This observation should be investigated further by employing more advanced levels of ab initio computations and other methods of multicomponent population analysis such as multicomponent quantum theory of atoms in molecules (MC‐QTAIM) that is the extension of Bader's quantum theory of atoms in molecules beyond the BO paradigm .…”

Section: Resultsmentioning

confidence: 99%

“…The spin-density distributions are delocalized among N3, C5, and C8 in Mu-C2-A/G adducts, complying with the virtual coplanarity of the double rings. the BO paradigm [122][123][124][125][126][127] .…”

Section: Purine Adductsmentioning

confidence: 99%

How intrinsic nuclear nonadiabaticity affects molecular structure, electronic density, and conformational stability: Insights from the multicomponent DFT calculations of Mu/H isotopologues

Int J of Quantum Chemistry

Jalili

2018

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In the present work, the formalism of the multicomponent density functional theory is extended to study the open‐shell muoniated radicals of nucleic acid bases adenine, guanine, cytosine, thymine and uracil beyond the adiabatic paradigm. The derived methodology is used to characterize the stationary structures of all conceivable muoniated adducts based on the ab initio nuclear‐electronic approach, which is a mixed intermediate non‐adiabatic/adiabatic framework. The energies, geometries, atomic charges and spin‐density distributions of the muoniated species are scrutinized against their hydrogenated congeners derived within the conventional adiabatic framework. The comparative analysis of the results determines the considerable impact of nuclear quantum effects on the molecular geometry, electronic density and conformational stability while underlining the fact that the extent of the geometrical and spin‐distribution variations upon muonium substitution could be significant and mass dependent.

“…[54][55][56] To deal with certain types of non-BO wavefunctions, like the NEO wavefunctions, an extended version of the QTAIM, termed the multi-component QTAIM (MC-QTAIM), has been recently introduced. [57][58][59][60][61][62][63][64][65][66][67][68][69] The MC-QTAIM methodology hasb een applied to molecules containing hydrogen isotopes as quantum waves, [60,67] as well as to positronic, [57][58][59] and muonic species. [66,68,69] In the present study,t he MC-QTAIM analysisi su sed to deciphert he AIM structure of m + -substituted malonaldehyde.…”

Section: Resultsmentioning

confidence: 99%

Muon‐Substituted Malonaldehyde: Transforming a Transition State into a Stable Structure by Isotope Substitution

Shahbazian

2016

Chemistry A European J

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Isotopes ubstitutionsa re usually conceived to play am arginal role on the structure and bondingp attern of molecules. However,arecent study [Angew.C hem. Int. Ed. 2014, 53,1 3706-13709; Angew.C hem. 2014, 126,1 3925-13929]f urther demonstrates that upon replacing ap roton with ap ositively charged muon, as the lightest radioisotope of hydrogen, radical changes in the nature of the structure and bonding of certains peciesm ay take place. The present report is ap rimary attemptt oi ntroduce another example of structural transformation on the basis of the malonaldehyde system.A ccordingly,u pon replacing the protonb etween the two oxygen atoms of malonaldehydew ith the positively charged muon as erious structuralt ransformationi so bserved. By using the ab initio nuclear-electronic orbitaln onBorn-Oppenheimer procedure, the nuclear configuration of the muon-substituted speciesi sd erived. The resulting nuclear configuration is much more similart ot he transition state of the proton transferi nm alonaldehyde rather than to the stable configuration of malonaldehyde. The comparison of the "atoms in molecules" (AIM) structureoft he muon-substituted malonaldehyde and the AIM structureo ft he stable and the transition-state configurations of malonaldehyde also unequivocally demonstrates substantial similarities of the muon-substituted malonaldehydet ot he transition state.