## Abstract

Lowest-energy structures, the distribution of isomers, and their molecular properties depend significantly on geometry and temperature. Total energy computations using DFT methodology are typically carried out at a temperature of zero K; thereby, en-tropic contributions to the total energy are neglected, even though functional materials work at finite temperatures. In the present study, the probability of the occurrence of one particular Be4B8 isomer at temperature T is estimated by employing Gibbs free energy computed within the framework of quantum statistical mechanics and nanothermody-namics. To identify a list of all possible low-energy chiral and achiral structures, an ex-haustive and efficient exploration of the potential/free energy surfaces is carried out using a multi-level multistep global genetic algorithm search coupled with DFT. In addition, we discuss the energetic ordering of structures computed at the DFT level against single-point energy calculations at the CCSD(T) level of theory. The total VCD/IR spectra as a function of temperature are computed using each isomer’s probability of occurrence in a Boltzmann-weighted superposition of each isomer’s spectrum. Additionally, we present chemical bonding analysis using the adaptive natural density partitioning method in the chiral putative global minimum. The transition state structures and the enantiomer–en-antiomer and enantiomer–achiral activation energies as a function of temperature evidence that a change from an endergonic to an exergonic type of reaction occurs at a temperature of 739 K.

Original language | English |
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Article number | 3953 |

Journal | Molecules |

Volume | 26 |

Issue number | 13 |

DOIs | |

State | Published - 1 Jul 2021 |

### Bibliographical note

Funding Information:C.E.B.-G. thanks Conacyt for the scholarship (860052). E.R.-C. thanks Conacyt for the scholarship (1075701). T.P.-A. thanks DCQB. We are grateful to Carmen Heras and L.C.C. Daniel Mendoza for granting us access to their clusters and computational support. Computational resources for this work were provided by the High-Performance Computing Area of the University of Sonora. We are also grateful to the computational chemistry laboratory for providing computational resources, ELBAKYAN, and PAKAL supercomputers. Powered@NLHPC: this research was partially supported by the supercomputing infrastructure of the NLHPC (ECM-02). M.F.M.-d.-C.-S. and C.C.Q. acknowledge the University (UdeG) network mobility from CUCi to CUCI.

Publisher Copyright:

© 2021 by the authors. Licensee MDPI, Basel, Switzerland.

## Keywords

- Adaptive natural density partitioning method
- Be4B8
- Beryllium–boron cluster
- Boltzmann factors
- Density functional theory
- Enthalpy
- Entropy
- Genetic algorithm
- Gibbs free energy
- Global minimum
- IR spectra
- Nanothermodynamics
- Quantum statistical mechanics
- Tempera-ture
- Thermochemistry
- Vibrational circular dichroism