The Antoine equation is a simple model for describing the vapor pressure of a pure substance. These data are for the vapor pressure of heavy water (deuterium oxide). Note that the standard boiling point of heavy water (rightmost point, VP = 760 torr) is a bit higher than for normal water (BP = 100 C).
Ref.: Lange's Handbook of Chemistry, 16th ed., table 1.51, 2005.
Here, we illustrate a logarithmic axis for an ordinate that spans three orders of magnitude.