Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
Philos Trans A Math Phys Eng Sci. 2013 Jun 3;371(1994):20110582. doi: 10.1098/rsta.2011.0582. Print 2013 Jul 13.
Numerical simulations examining chemical interactions of water molecules with forsterite grains have demonstrated the efficacy of nebular gas adsorption as a viable mechanism for water delivery to the terrestrial planets. Nevertheless, a comprehensive picture detailing the water-adsorption mechanisms on forsterite is not yet available. Towards this end, using accurate first-principles density functional theory, we examine the adsorption mechanisms of water on the (001), (100), (010) and (110) surfaces of forsterite. While dissociative adsorption is found to be the most energetically favourable process, two stable associative adsorption configurations are also identified. In dual-site adsorption, the water molecule interacts strongly with surface magnesium and oxygen atoms, whereas single-site adsorption occurs only through the interaction with a surface Mg atom. This results in dual-site adsorption being more stable than single-site adsorption.
数值模拟研究了水分子与镁橄榄石颗粒的化学相互作用，证明了星云中气体吸附作为向类地行星输送水的可行机制的有效性。然而，目前还没有详细描述镁橄榄石上水吸附机制的全面情况。为此，我们使用精确的第一性原理密度泛函理论，研究了水在镁橄榄石(001)、(100)、(010)和(110)表面的吸附机制。虽然发现离解吸附是最有利的能量过程，但也确定了两种稳定的缔合吸附构型。在双位吸附中，水分子与表面镁和氧原子强烈相互作用，而只有通过与表面 Mg 原子相互作用才能发生单吸附。这导致双位吸附比单吸附更稳定。
