Electronic and magnetic structure of CsV${}_2$O${}_5$

We have studied the electronic structure of the spin-gapped system CsV${}_2$O${}_5$ by means of an ab initio calculation. Our analysis and a re-examination of the susceptibility data indicate that the behavior of this system is much closer to that of an alternating spin-1/2 antiferromagnetic chain with significant inter-dimer coupling and weaker inter-chain couplings than that of isolated dimers as was initially proposed. Comparison to the vanadate family members ${\alpha }^{\mathrm{\prime }}$-NaV${}_2$O${}_5$, $\gamma$-LiV${}_2$O${}_5$ and isostructural compounds like (VO)${}_2$P${}_2$O${}_7$ (VOPO) is discussed.