  We have shown that the observed drastic violation of the Curie-Weiss law in
Na2V3O7, reported in Phys. Rev. Lett. 90 (2003) 167202, is caused by
conventional crystal-field interactions and the intra-atomic spin-orbit
coupling of the V4+ ion. The fine discrete electronic structure of the 3d1
configuration, with a substantial orbital moment, is the reason for anomalous
low-temperature properties of Na2V3O7. According to the Quantum Atomistic
Solid-State Theory (QUASST) Na2V3O7 is expected to exhibit pronounced
heavy-fermion phenomena at low temperatures. This study confirm our earlier
claim that the orbital moment has to be unquenched in description of 3d-atom
compounds.
  PACS: 71.70.E, 75.10.D
  Keywords: crystal-field interactions, spin-orbit coupling, orbital moment,
Na2V3O7
