A Computational Study of H-Fe Vacancy Interaction

CAROLINA PISTONESI; ALEJANDRO J. GARCÍA; GRACIELA BRIZUELA; ALFREDO JUAN

JOURNAL OF PHYSICS - D (APPLIED PHYSICS)

IOP PUBLISHING LTD

Año: 1998 vol. 31 p. 588 - 594

0022-3727

The semi-empirical atom superposition and electron delocalization molecular orbital (ASED-MO) theory was used to study the H–Fe interaction near a Fe vacancy. Calculations were carried out using clusters of the type Fe86 and simulating the absorption of a hydrogen atom near a vacancy located at the centre of the cluster. The formation of H–H pairs was also considered. Our calculations involve a system in which experiments are difficult to perform and could contribute to a better understanding or insight based on microscopic exploration. The results indicate that in general the H–Fe interaction gets stronger when the H atom is close to the vacancy but not at its centre due to a strong indirect interaction mediated by the Fe matrix. Minima regions are obtained at eccentric positions. A H–H pair is suggested to be formed near the vacancy region. The relaxation of the first neighbour Fe atoms towards the vacancy is also addressed in the presence and absence of H. For all situations studied, the most stable configuration corresponds to a cluster contraction.