Equilibrium sulfur isotope fractionations of several important sulfides

Zhang, Jixi

doi:10.2343/geochemj.2.0623

Cited by 10 publications

(12 citation statements)

References 64 publications

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“…The amount of virtual charges needed to be added to the mineral fragments should be equal to the amount of research systems to ensure the electrical neutrality. This approach has been reported in numerous studies [41,42,[48][49][50]. It shows that the theoretical calculation method adopted by this study is feasible and reasonable.…”

Section: Fractionation Factors Of Ga-bearing Mineralssupporting

confidence: 53%

“…The results of this study show that, although these four different structures with the same number of water molecules surrounded in totally four different, their RPFR is slightly different. According to the previous research results [41,42], when the number of outer water molecules increases to 30, the RPFR of the water molecule cluster tends to converge. That is, the RPFR of 24 water molecules has the same value to the RPFR of 30 water molecules.…”

Section: The 1000ln(rpfr)s Of Eleven Ga-bearing Mineralsmentioning

confidence: 74%

“…The frequencies calculated using the molecular cluster method cannot be compared with experimental frequencies. In my previous study [41], gaseous sulfur ( 32 S) molecules' frequencies were calculated with the same method and compared to experimental frequencies.…”

Section: Resultsmentioning

confidence: 99%

“…The core problem is how to obtain the simple harmonic vibration frequency of minerals or other matters. In this study, Ga-bearing minerals are simulated by a volume variable cluster model (VVCM) method (a kind of cluster-model based method) [41,42,[48][49][50]. With the rapid development of computing power, molecular clusters with dozens, hundreds, or even thousands of atoms can be modeled very well.…”

Section: The Vvcm Methodsmentioning

confidence: 99%

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Gallium isotope fractionations between several important Gallium- bearing minerals and aqueous solutions

Zhang

2022

Preprint

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This study predicts the equilibrium isotope fractionation factors for some important Ga-bearing species, including major minerals, aqueous solutions and gas phase systems. Equilibrium isotope fractionations of Ga are investigated by using first-principles quantum chemistry method at B3LYP/6-311+G(d) level. The isotope fractionation factors of minerals Orthoclase, Albite, Quartz, Kaolinite, Forsterite, Montmorillonite, Gibbsite, Cassiterite, Aragonite, Sphalerite and Calcite are calculated with the method of the volume variable cluster model (VVCM). The 1000ln(RPFR)s of these minerals decrease in the following order: Orthoclase>Albite>Quartz>Kaolinite>Forsterite>Montmorillonite>Gibbsite>Cassiterite>Aragonite>Sphalerite>Calcite. The solvation effect of Ga3+-bearing aqueous species is modeled by the water-droplet method. The 1000ln(RPFR)s of Ga3+-bearing aqueous species decrease in the order of [Ga(OH)4]->[Ga(OH)3]>[Ga(OH)]2+>[Ga(OH)2]+>[Ga(H2O)6]3+. The calculation results show that equilibrium isotope fractionations of Ga between different minerals, solutions and gas phases are appreciable. Among solid minerals, gallium isotope fractionation has the largest value between orthoclase type and calcite type minerals. Ga isotopic fractionation value between these two minerals can reach 3.18 per mil at 100 °C. Ga isotope fractionation between Ga-bearing aqueous species and minerals are important to give some information about the different geochemistry processes such as surficial geochemistry. This study has provided those important Ga isotope fractionation factors.

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Section: Fractionation Factors Of Ga-bearing Mineralssupporting

confidence: 53%

Section: The 1000ln(rpfr)s Of Eleven Ga-bearing Mineralsmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: The Vvcm Methodsmentioning

confidence: 99%

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Gallium isotope fractionations between several important Gallium- bearing minerals and aqueous solutions

Zhang

2022

Preprint

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“…Finally, the frequency calculations are performed only for the small core. As an alternative, the volume variable cluster model (VVCM) method was proposed by Liu [ 21 ], which was developed during the optimization of silicates, carbonates, oxides, hydroxides, and sulfides [ 22 – 28 ]. In contrast to the embedded cluster model, in the VVCM model all atoms of the cluster are geometrically optimized, and all or partial atoms are involved in the calculations of the vibrational frequency according to the computational cost.…”

Section: Introductionmentioning

confidence: 99%

Improved volume variable cluster model method for crystal-lattice optimization: effect on isotope fractionation factor

Wang

Xing

et al. 2022

Geochem Trans

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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 $$\Delta ^{30/28} {\text{Si}}_{{{\text{Qtz-H}}_{4} {\text{SiO}}_{4} }} = 2.20{\permil} $$ Δ 30 / 28 Si Qtz-H 4 SiO 4 = 2.20 ‰ , $$\Delta^{18/16} {\text{O}}_{ {\text{Qtz}}{-} ( {\text{H}}_{2} {\text{O}} )_{\text{n}}} = 36.05{\permil}$$ Δ 18 / 16 O Qtz - ( H 2 O ) n = 36.05 ‰ , $$\Delta^{66/64} {\text{Zn}}_{ {\text{Zn}} {-} {\text{Al LDH-Zn}} ( {\text{H}}_{2} {\text{O}} )_{\text{n}}^{2+}} = 1.12{\permil}$$ Δ 66 / 64 Zn Zn - Al LDH-Zn ( H 2 O ) n 2 + = 1.12 ‰ and $$\Delta^{114/110} {\text{Cd}}_{ {\text{(Cd--Cal)-Cd}} ( {\text{H}}_{2} {\text{O}} )_ {\text{n}}^{2 +} } = - 0.26{\permil}$$ Δ 114 / 110 Cd (Cd--Cal)-Cd ( H 2 O ) n 2 + = - 0.26 ‰ respectively. These results strongly support the reliability of the improved VVCM method for geometric optimization of molecular clusters.

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Sulfur isotopic systematics of hydrothermal precipitates in the Okinawa Trough: Implication for the effect of sediments and magmatic volatiles

Wang,

Li,

et al. 2024

Chemical Geology

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Equilibrium sulfur isotope fractionations of several important sulfides

Cited by 10 publications

References 64 publications

Gallium isotope fractionations between several important Gallium- bearing minerals and aqueous solutions

Gallium isotope fractionations between several important Gallium- bearing minerals and aqueous solutions

Improved volume variable cluster model method for crystal-lattice optimization: effect on isotope fractionation factor

Sulfur isotopic systematics of hydrothermal precipitates in the Okinawa Trough: Implication for the effect of sediments and magmatic volatiles

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