Why sp²‐like nanosilicons should not form: Insight from quantum chemistry

Abstract

The odd‐electron molecular theory, which takes into account the electron correlation, has been applied for a comparative consideration of sp2 nanocarbons and their siliceous analogues. Four characteristic quantities that involve the energy misalignment, the number of effectively unpaired electrons, the squared spin value, and CC and SiSi chemical bond lengths have been suggested to classify the extent of the odd electron correlation in both families. Providing a considerable enlargement of the internuclear distances, the electron correlation in siliceous species is extremely strong thus resulting in complete radicalization of the species and proving the impossibility of their existence at ambient conditions in contrast to carboneous ones that are not so strong correlated. © 2012 Wiley Periodicals, Inc.

Advances in Quantum Methods and Applications in Chemistry, Physics, and Biology

“…Wilson suggested [88] that using the clamped-nuclei Hamiltonian instead of the full one in (1.48) to define the potential might avoid the spikes but Hunter in [86] showed why this was unlikely to be the case, and Cassam-Chenai [89] repeated the work of Czub and Wolniewicz using a clamped-nuclei electronic Hamiltonian and showed that exactly the same spiky behaviour occurred.…”

“…Let us conclude that the OPT method has been also successfully applied to correct description of the resonances of the Zeeman effect in a strong magnetic field, crossed electric and magnetic fields, the resonances in molecular systems, as well as descriptions of resonant states in nuclear systems such as the resonances of the compound nucleus and the resonances arising from the collision of heavy ions (nuclei), accompanied by the electron-positron pairs production (look the details in Refs. [6,80,[83][84][85][86][87][88][89][90][91]). …”

“…These explanations are obtained on the same platform based on quite a few concepts involving the odd electrons of the graphene benzenoid units and their correlation due to weak interaction. Outside the paper, there are still questions concerning the chemical topology of graphene [84,85], different aspects concerning graphene quantum dots [86,87], the silicene as siliceous counterpart of graphene [88,89], the graphene catalytic activity [90,91], and so forth. The molecular theory of graphene is very successful in dealing with all these issues, not being concentrated on numbers but giving the main attention to clearly seen trends.…”

Stretching and Breaking of Chemical Bonds, Correlation of Electrons, and Radical Properties of Covalent Species

“…Briefly summarizing, the graphene radicalization is mainly concentrated on the circumference and thus is usually well inhibited by the termination of edge atoms. As for silicene, the termination of edge atoms is not enough to inhibit its high radicalization since the latter remains still high on the atoms in basal plane [31,52,53] due to which free standing one-atom thick silicene sheet cannot exist under ambient conditions. Experimental evidence of 'silicene' is related to the hexagon-patterned monolayers of silicon atoms on either Ir(111) or Ag(111) surfaces (see review [44] and references therein) chemically bound with substrates.…”

π conjugation in the epitaxial Si(111)- 3×3 surface: Unconventional “bamboo hat” bonding geometry for Si

“…Weak π-conjugation has been found in Si(111)-(2×1) surface within a linear chain structure [6][7][8], but the most typical hexagonal ring structure has never been seen. This underlies the difficulty in experimentally synthesizing the elusive freestanding form of silicene [9][10][11][12][13][14].…”