PERIMETRIC SCALE-SHAPE COORDINATES FOR TRIATOMIC-MOLECULES

Perimetric nuclear coordinates of a triatomic molecule treat all three nuclei equivalently and are not subject to the triangle conditions. T hrough an appropriate orthogonal transformation they can be separated into one scale coordinate, viz., the circumference, and two shape coor dinates, which are determined by the angles. The parameter space of th e shape coordinates is an equilateral triangle. The basic formulas are given and the relationship between points in coordinate space and mol ecular shapes are elucidated.