Surface atomic forces and multilayer relaxation of W(001), W(110) and Fe/W(110)

Calculations of the atomic forces, magnetic moments and relaxations of the surfaces of W and of a Fe monolayer on W have been performed in the framework of the full potential LAPW method and in terms of the Car-Parrinello approach. The surface is found to be contracted by about 4% for W(100) and about 0.8% for W(110) as compared with the bulk spacing in agreement with recent LEED experiments. Estimates of surface energy of W(001) and W(110) as well as surface core-level shifts are in accordance with experiments, too. A qualitative Pettifor-like charge-transfer model has been used to discuss the relaxations of the surface of tungsten and iron monolayer. Quantitative estimates show that deposition of the Fe monolayer to the tungsten surface decreases the surface tension discernibly relieving the tensile surface stress of the clean W(110) surface. (C) 1998 Published by Elsevier Science B.V. All rights reserved.