A Density Functional Theory Study of the Charge State of Hydrogen in Metal Hydrides

作者：Aboud Shela; Wilcox Jennifer^*

来源：Journal of Physical Chemistry C, 2010, 114(24): 10978-10985.

DOI：10.1021/jp911811r

Density functional theory and Bader charge analyses were used to investigate the charge state of hydrogen in vanadium, niobium, tantalum, palladium, and niobium-palladium alloys. Over a range of concentrations and hydrogen-site configurations, it is found that hydrogen consistently acquires a net charge of between approximately -0.51e and -0.64e in the pure group 5 metals compared with a significantly smaller value of 0.3e in palladium. Although there is indirect evidence that the electronic charge plays a role in the solubility and diffusivity of hydrogen in the group 5 metals, this is the first work to quantify the value of the charge. Hydrogen tends to migrate to regions of the metal lattice that minimize its overall charge density, which generally corresponds to the T-site in the bcc metals. It is found that the charge of hydrogen at the O-site of vanadium can be slightly lower due to lattice deformation and may explain the occupation of both T- and O-sites in vanadium hydrides.

• 出版日期2010-6-24