c This subroutine calculates unit vectors of a local reference system
c defined by atoms (i2), (i3), and (i4). The x axis is the axis from
c atom (i3) to atom (i2), and the xy plane is the plane defined by atoms
c This subroutine calculates unit vectors of a local reference system
c defined by atoms (i2), (i3), and (i4). The x axis is the axis from
c atom (i3) to atom (i2), and the xy plane is the plane defined by atoms