First-principles calculation of H/D isotopic fractionation between hydrous minerals and water
Abstract
Hydrogen fractionation laws between selected hydrous minerals (brucite, kaolinite, lizardite, and gibbsite) and perfect water gas have been computed from first-principles quantum-mechanical calculations. The β-factor of each phase was calculated using the harmonic phonon dispersion curves obtained within density functional theory. All the fractionation laws show the same shape, with a minimum between 200 °C (brucite) and 500 °C (gibbsite). At low temperatures, the mineral/liquid water fractionation laws have been obtained using the experimental gas/liquid water fractionation laws. The resulting fractionation laws systematically overestimate measurements by 15‰ at low temperatures to 8‰ at ≈400 °C. Based on this general agreement, all calculated laws were empirically corrected with reference to brucite/water data. These considerations suggest that the experimental or natural calibrations by Xu and Zheng (1999) and Horita et al. (2002) (brucite/water), Gilg and Sheppard (1996) (kaolinite/water), Wenner and Taylor (1973) (lizardite/water), and in some extents Vitali et al. (2001) (gibbsite/water) are representative of equilibrium fractionations. Besides, internal isotopic fractionation of hydrogen between inner-surface and inner hydroxyl groups has been computed for kaolinite and lizardite. The obtained fractionation is large, of opposite sign for the two systems (respectively, -23‰ and +63‰ at 25 °C) and is linear in T⁻². Internal fractionation of hydrogen in TO phyllosilicates might thus be used in geothermometry.
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BibTeX
@article{meheut2026firstprinciples,
title = {{First-principles calculation of H/D isotopic fractionation between hydrous minerals and water}},
author = {Merlin Méheut and Michele Lazzeri and Etienne Balan and Francesco Mauri},
journal = {Geochimica et Cosmochimica Acta},
year = {2026},
month = sep,
doi = {10.1016/j.gca.2010.04.020},
url = {https://insu.hal.science/insu-03605315v1},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - First-principles calculation of H/D isotopic fractionation between hydrous minerals and water
AU - Merlin Méheut
AU - Michele Lazzeri
AU - Etienne Balan
AU - Francesco Mauri
PY - 2026
DA - 2026/09/02
JO - Geochimica et Cosmochimica Acta
DO - 10.1016/j.gca.2010.04.020
UR - https://insu.hal.science/insu-03605315v1
AB - Hydrogen fractionation laws between selected hydrous minerals (brucite, kaolinite, lizardite, and gibbsite) and perfect water gas have been computed from first-principles quantum-mechanical calculations. The β-factor of each phase was calculated using the harmonic phonon dispersion curves obtained within density functional theory. All the fractionation laws show the same shape, with a minimum between 200 °C (brucite) and 500 °C (gibbsite). At low temperatures, the mineral/liquid water fractionation laws have been obtained using the experimental gas/liquid water fractionation laws. The resulting fractionation laws systematically overestimate measurements by 15‰ at low temperatures to 8‰ at ≈400 °C. Based on this general agreement, all calculated laws were empirically corrected with reference to brucite/water data. These considerations suggest that the experimental or natural calibrations by Xu and Zheng (1999) and Horita et al. (2002) (brucite/water), Gilg and Sheppard (1996) (kaolinite/water), Wenner and Taylor (1973) (lizardite/water), and in some extents Vitali et al. (2001) (gibbsite/water) are representative of equilibrium fractionations. Besides, internal isotopic fractionation of hydrogen between inner-surface and inner hydroxyl groups has been computed for kaolinite and lizardite. The obtained fractionation is large, of opposite sign for the two systems (respectively, -23‰ and +63‰ at 25 °C) and is linear in T⁻². Internal fractionation of hydrogen in TO phyllosilicates might thus be used in geothermometry.
SN - 0016-7037
SN - 1872-9533
ER -