TY - JOUR

T1 - Deductive molecular mechanics of carbon allotropes (Review Article)

AU - Popov, I. V.

AU - Chugreev, A. L.

AU - Dronskowski, R.

PY - 2020/7

Y1 - 2020/7

N2 - The relative stability of diamond and graphite is readdressed from a new perspective of the deductive molecular mechanics. Unlike most theoretical studies done numerically, we use an ana-lytic model to get an insight into fundamental reasons for quasi-degeneracy of these allotropes with very different bonding pat-terns. We derive the relative energies of the allotropes and prove several general statements about the structure of materials. Our analysis yields a quasi-degenerate electronic ground state for graphite and diamond at 0 K. Numerical estimates based on it are in an astonishingly good agreement with experimental data and recent results of numeric modeling, although obtained with a drastically smaller numerical effort. An extension of the proposed treatment to the allotropes of silicon proves to be very successful as well. Following similar lines, we extended the proposed treat-ment to the four-coordinated allotropes of carbon and developed the software package Adamas which is capable to calculate ener-gies of allotropes and their elastic properties (elastic moduli). Similarly, to the case of diamond and graphene, some general statements could be proven within the deductive molecular me-chanics setting. Specifically, it is shown that among the four-coordinated allotropes the cubic diamond structure represents the true minimum. In the cases of allotropes that contain some C-C bonds stronger than those in diamond, the energy gain is compen-sated by the mandatory presence of weaker bonds in the same allotrope finally leading to the overall increase of the energy rela-tive to the diamond.

AB - The relative stability of diamond and graphite is readdressed from a new perspective of the deductive molecular mechanics. Unlike most theoretical studies done numerically, we use an ana-lytic model to get an insight into fundamental reasons for quasi-degeneracy of these allotropes with very different bonding pat-terns. We derive the relative energies of the allotropes and prove several general statements about the structure of materials. Our analysis yields a quasi-degenerate electronic ground state for graphite and diamond at 0 K. Numerical estimates based on it are in an astonishingly good agreement with experimental data and recent results of numeric modeling, although obtained with a drastically smaller numerical effort. An extension of the proposed treatment to the allotropes of silicon proves to be very successful as well. Following similar lines, we extended the proposed treat-ment to the four-coordinated allotropes of carbon and developed the software package Adamas which is capable to calculate ener-gies of allotropes and their elastic properties (elastic moduli). Similarly, to the case of diamond and graphene, some general statements could be proven within the deductive molecular me-chanics setting. Specifically, it is shown that among the four-coordinated allotropes the cubic diamond structure represents the true minimum. In the cases of allotropes that contain some C-C bonds stronger than those in diamond, the energy gain is compen-sated by the mandatory presence of weaker bonds in the same allotrope finally leading to the overall increase of the energy rela-tive to the diamond.

KW - Diamond

KW - Graphene

KW - Graphite

KW - Hybrid orbitals

KW - Lonsdaleite

KW - Quantum chemical calculations

UR - http://www.scopus.com/inward/record.url?scp=85090035493&partnerID=8YFLogxK

M3 - Book/Film/Article review in journal

AN - SCOPUS:85090035493

VL - 46

SP - 781

EP - 798

JO - Fizika Nizkikh Temperatur

JF - Fizika Nizkikh Temperatur

SN - 0132-6414

IS - 7

ER -