Cone angle θ is half the opening angle of the cone. Since it makes no difference, if the opening of the cone points upward or downward, the cone angle can be limited to values between 0o and 90o. When choosing the option to define the interaction tensor relative to the cone system, θ corresponds to the polar angle of z(PAS) in the cone system. If a molecular frame is used as a reference for the interaction tensor, θ corresponds to the angle between the molecular z-axis z(MF) and the cone axis. (see topic ⇒ Tensor relative to)