Exchange interactions and theoretical analysis of (31)P NMR spectra in VO(HPO(4)).0.5H(2)O

Based on combined DFT/broken symmetry approach, a theoretical analysis of the exchange interactions in the VO(HPO(4)).0.5H(2)O solid is performed. Depending on the crystallographic structures reported in the literature, two very different spin models are formulated. In addition, a complete fit of the temperature-dependent (31)P NMR chemical shift is performed to determine exchange and hyperfine constants. The magnetic models used in the fit are those obtained by our theoretical calculations. The comparison between the calculated and fitted exchange constants confirms the adequacy of an isolated dimer model and rules out the alternating antiferromagnetic chain model for VO(HPO(4)).0.5H(2)O.