Theoretical Momentum Distributions in Nb_3O_3

概要

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The theoretical momentum density distributions (MDD) in Nb0 measured by Corn-pton profile experiments and positron annihilation techniques are calculated by theAPW method. The difference between Compton profile and the positron annihilationprofile comes from the trapping of positrons at vacancies. The trapping effect makesthe positron annihilation profiles broader a little. In order to express the ground stateof a positron in Nb0 by the APW method, 33 augmented plane waves with at leastthree angular momentum quantum number terms (/=0, 2 and 4) are found to benecessary. Both the Compton profiles and positron annihilation profiles showanisotropies, but those structures are different from each other. It is shown that theanisotropies are due to the fully occupied bands as well as to the topology of the Fermi surfaces. But folded MDD's to the first Brillouin zone show the characteristic struc-lures of the Fermi surfaces very well.
社団法人日本物理学会の論文
1986-04-15