Ab initio evaluation of local effective interactions in ${\alpha }^{\prime }Na{V}_2{O}_5$

Abstract

We will present the numerical evaluation of the hopping and magnetic exchange integrals for a nearest-neighbor $t-J$ model of the quarter-filled ${\alpha }^{\prime }Na{V}_2{O}_5$ compound. The effective integrals are obtained from valence-spectroscopy {\em ab initio} calculations of embedded crystal fragments (two $V{O}_5$ pyramids in the different geometries corresponding to the desired parameters). We are using a large configurations interaction (CI) method, where the CI space is specifically optimized to obtain accurate energy differences. We show that the ${\alpha }^{\prime }Na{V}_2{O}_5$ system can be seen as a two-dimensional asymmetric triangular Heisenberg lattice where the effective sites represent delocalized $V-O-V$ rung entities supporting the magnetic electrons.

24 pages, 5 figures

References in corpus (1)

• Anomalous thermal conductivity of NaV2O5 as compared to conventional spin-Peierls system CuGeO3

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