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Markelova AN, Simonova GV, Kalashnikova DA, Volkov YV. Long-Term Variations of δ13С in Tree Ring Cellulose of the Ob-Tom Interfluve. CONTEMP PROBL ECOL+ 2022. [DOI: 10.1134/s1995425522030088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Wang YF, Ji XY, Xing LC, Wang PD, Liu J, Zhang TD, Zhao HN, He HT. Improved volume variable cluster model method for crystal-lattice optimization: effect on isotope fractionation factor. GEOCHEMICAL TRANSACTIONS 2022; 23:1. [PMID: 35598206 PMCID: PMC9124387 DOI: 10.1186/s12932-022-00078-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 03/31/2022] [Indexed: 06/15/2023]
Abstract
The isotopic fractionation factor and element partition coefficient can be calculated only after the geometric optimization of the molecular clusters is completed. Optimization directly affects the accuracy of some parameters, such as the average bond length, molecular volume, harmonic vibrational frequency, and other thermodynamic parameters. Here, we used the improved volume variable cluster model (VVCM) method to optimize the molecular clusters of a typical oxide, quartz. We documented the average bond length and relative volume change. Finally, we extracted the harmonic vibrational frequencies and calculated the equilibrium fractionation factor of the silicon and oxygen isotopes. Given its performance in geometrical optimization and isotope fractionation factor calculation, we further applied the improved VVCM method to calculate isotope equilibrium fractionation factors of Cd and Zn between the hydroxide (Zn-Al layered double hydroxide), carbonate (cadmium-containing calcite) and their aqueous solutions under superficial conditions. We summarized a detailed procedure and used it to re-evaluate published theoretical results for cadmium-containing hydroxyapatite, emphasizing the relative volume change for all clusters and confirming the optimal point charge arrangement (PCA). The results showed that the average bond length and isotope fractionation factor are consistent with those published in previous studies, and the relative volume changes are considerably lower than the results calculated using the periodic boundary method. Specifically, the average Si-O bond length of quartz was 1.63 Å, and the relative volume change of quartz centered on silicon atoms was - 0.39%. The average Zn-O bond length in the Zn-Al-layered double hydroxide was 2.10 Å, with a relative volume change of 1.96%. Cadmium-containing calcite had an average Cd-O bond length of 2.28 Å, with a relative volume change of 0.45%. At 298 K, the equilibrium fractionation factors between quartz, Zn-Al-layered double hydroxide, cadmium-containing calcite, and their corresponding aqueous solutions were [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] respectively. These results strongly support the reliability of the improved VVCM method for geometric optimization of molecular clusters.
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Affiliation(s)
- Yan-Fang Wang
- School of Earth Science and Engineering, Hebei University of Engineering, Handan, 056038, China
| | - Xin-Yue Ji
- School of Earth Science and Engineering, Hebei University of Engineering, Handan, 056038, China
| | - Le-Cai Xing
- School of Earth Science and Engineering, Hebei University of Engineering, Handan, 056038, China
- Key Laboratory of Resource Survey and Research of Hebei Province, Hebei University of Engineering, Handan, 056038, China
| | - Peng-Dong Wang
- School of Earth Science and Engineering, Hebei University of Engineering, Handan, 056038, China
| | - Jian Liu
- School of Earth Science and Engineering, Hebei University of Engineering, Handan, 056038, China
| | - Tian-Di Zhang
- School of Earth Science and Engineering, Hebei University of Engineering, Handan, 056038, China
| | - Hao-Nan Zhao
- School of Earth Science and Engineering, Hebei University of Engineering, Handan, 056038, China
| | - Hong-Tao He
- School of Earth Science and Engineering, Hebei University of Engineering, Handan, 056038, China.
- Key Laboratory of Resource Survey and Research of Hebei Province, Hebei University of Engineering, Handan, 056038, China.
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