Examinando por Autor "Quiroz-Castillo, Jesus Manuel"
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Ítem Effects of temperature on enantiomerization energy and distribution of isomers in the chiral cu13 cluster(MDPI, 2021-09) Castillo-Quevedo, Cesar; Buelna-Garcia, Carlos Emiliano; Paredes-Sotelo, Edgar; Robles-Chaparro, Eduardo; Zamora-Gonzalez, Edgar; Martin-Del-campo-solis, Martha Fabiola; Quiroz-Castillo, Jesus Manuel; Del-Castillo-Castro, Teresa; Martínez-Guajardo, Gerardo; De Leon flores, Aned; Cortez Valadez, Manuel; Ortiz Chi, Filiberto; Gaxiola, Tulio; Castillo, Santos Jesus; Vásquez Espinal, Alejandro; Pan, Sudip; Cabellos, Jose LuisIn this study, we report the lowest energy structure of bare Cu13 nanoclusters as a pair of enantiomers at room temperature. Moreover, we compute the enantiomerization energy for the interconversion from minus to plus structures in the chiral putative global minimum for temperatures ranging from 20 to 1300 K. Additionally, employing nanothermodynamics, we compute the probabilities of occurrence for each particular isomer as a function of temperature. To achieve that, we explore the free energy surface of the Cu13 cluster, employing a genetic algorithm coupled with density functional theory. Moreover, we discuss the energetic ordering of isomers computed with various density functionals. Based on the computed thermal population, our results show that the chiral putative global minimum strongly dominates at room temperature. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Ítem Theoretical Prediction of Structures, Vibrational Circular Dichroism, and Infrared Spectra of Chiral Be4B8 Cluster at Different Temperatures(MDPI AG, 2021-07-01) Buelna-García, Carlos Emiliano; Robles-Chaparro, Eduardo; Parra-Arellano, Tristan; Quiroz-Castillo, Jesus Manuel; del-Castillo-Castro, Teresa; Martínez-Guajardo, Gerardo; Castillo-Quevedo, Cesar; de-León-Flores, Aned; Anzueto-Sánchez, Gilberto; Martin-del-Campo-Solis, Martha Fabiola; Mendoza-Wilson, Ana Maria; Vásquez-Espinal, Alejandro; Cabellos, Jose LuisLowest-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.