Deciphering the “chemical” nature of the exotic isotopes of hydrogen by the MC-QTAIM analysis: the positively charged muon and the muonic helium as new members of the periodic table

Abstract

This report is a primarily survey on the chemical nature of some exotic species containing the positively charged muon and the muonic Helium, i.e., the negatively charged muon plus helium nucleus, as exotic isotopes of hydrogen, using the newly developed multicomponent quantum theory of atoms in molecules (MC-QTAIM) analysis, employing ab initio non-Born-Oppenhiemer wavefunctions. Accordingly, the "atoms in molecules" analysis performed on various asymmetric exotic isotopomers of hydrogen molecule, recently detected experimentally [Science 331, 448 (2011)], demonstrates that both the exotic isotopes are capable of forming atoms in molecules and retaining the identity of hydrogen atom. Various derived properties of atomic basins containing muonic helium cast no doubt that apart from its short life time, it is a heavier isotope of hydrogen while the properties of basins containing the positively charged muon are more remote from those of the orthodox hydrogen basins, capable of appreciable donation of electrons as well as large charge polarization; however, with some tolerance, they may be categorized also as hydrogen basins though with a smaller electronegativity. All in all, present study also clearly demonstrates that the MC-QTAIM analysis is an efficient approach to decipher the chemical nature of species containing exotic constituents, hard to be elucidated by experimental and/or alternative theoretical schemes. KeywordsMuon; Muonic helium; quantum theory of atoms in molecules; exotic matter; non-BornOppenhiemer; multi-component systems 3

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

“…In line with the elongation of the oxygen–oxygen internuclear distance, the distance between the Bq center and the oxygen nuclei in structure 3 is approximately 0.05–0.06 Å longer than the corresponding distance in structure 2 . Interestingly, in the previous studies it was also observed that upon replacing a proton with a μ + , independent from the nature of the heavier atom involved in the bond, the mean internuclear distances generally elongate by approximately 0.05 Å . So, this elongation manifests the nature of the μ + and one may conceive structure 3 emerging from replacing the proton of structure 2 by a μ + and upon this isotopic substitution, the transition state transforms into a stable structure.…”

Some implications of the Hartree product treatment of the quantum nuclei in the ab initio nuclear–electronic orbital methodology

“…On the other hand, the NEO methodology has been also used to study molecular systems containing exotic particles like positrons [13,15,17,42], or the positively charged muons [23][24][25][26]. In the case of the muonic (and positronic) systems the use of the NEO methodology is inevitable from outset since no "safe" adiabatic background has been justified yet and thus any comprehensive "muon-specific computational chemistry" must be based on the NEO.…”

“…, which has also been used in some previous ab initio NEO-HF calculations [23][24][25][26]36], is employed herein. In this function the two parameters, to be determined for each quantum nucleus, are the exponent, n  , and the center of the location of the function in space, , n c R  .…”

“…The Nuclear-electronic orbital (NEO) is particularly a promising non-BO ab initio methodology since various types of the NEO wavefunctions have been proposed with varying degree of complexity [1,[10][11][12][13][14][15][16][17][18][19][20][21][22]. Very recently, the NEO has also been successfully utilized for molecules containing exotic light quantum particles like the positively charged muons [23][24][25][26]. In this methodology certain types of nuclei or exotic light quantum particles are treated as quantum waves while adequate numbers of clamped nuclei are retained to avoid the complications emerging from treating total translational and rotational dynamics [27,28].…”

Six questions on topology in theoretical chemistry

“…I am personally working on the extension of the QTAIM beyond the Born-Oppenhiemer paradigm as well as for exotic species [83], I must emphasize that concomitant topological analysis is central to decipher "atoms in molecules" (AIM) structure in these domains. Traditionally, these domains were not considered to be amenable to AIM analysis so the topological approach of the extended QTAIM (termed multi-component QTAIM) is a novel application of the topological analysis that unifies the AIM concept of a large (and traditionally irrelevant) classes of systems (for a recent example see: [84]). Time-dependent topological analysis is another area that may have a bright future when considering molecular dynamics and time-dependent Schrödinger equation for chemical reactions, even applications beyond chemistry are foreseeable (for some interesting examples of nonorthodox applications of the ELF analysis see: [85,86]).…”