  The structural properties of Na2RuO3 under pressure are studied using density
functional theory within the generalized gradient approximation (GGA). We found
that one may expect a structural transition at ~ 3 GPa. This structure at the
high-pressure phase is exactly the same as the low-temperature structure of
Li2RuO3 (at ambient pressure) and is characterized by the P21/m space group. Ru
ions form dimers in this phase and one may expect strong modification of the
electronic and magnetic properties in Na2RuO3 at pressure higher than 3 GPa.
