Weblab allows not only motion on one cone but can also treat more complicated motions like jumps on two or three cones. In the Cone Settings menu the different cones are denoted as Cone 1 and Cone 2 when two cones are selected and as Cone 0, Cone 1 and Cone 2 for three cones. For each cone you have to specify the number of sites, cone angle and jump angle (sites <=3), as well as an euler angle α for the orientation of the axes system of each cone.
The sketch on the left shows the situation for two cones. A fragment of a molecular structure consisting of two C-C bonds. One CH- (or CH²) bond and the corresponding interaction tensor (blue elipsoid) is moving on cone #1 defined by cone axis z1, cone angle θ1 and jump angle ϕ1.This C-C bond along z1 is moving itself on a second cone (cone #2) with half opening angle θ2 and jump angle ϕ2. The euler angle α for cone 1 describes the relative orientation of the PAS tensor with respect to cone 1. It is the azimutal polar angles of z1 in the PAS-axes system. It is only necessary if the tensor on the PAS system is not axial symmetric.

The euler angle α for cone 2 is the azimutal polar angles of z2 in the cone 1 system. It is essential, f the motion in cone 1 yields an average tensor with η ≠ 0;

Weblab supports motions on more than one cone under the following conditions:

  1. All motions are uncorrelated.
  2. The movements on cone #1 and, if necessary, on cone #0 are much faster than those on cone #2.
  3. The z-axis of the interaction tensor is lying on the cone shell of cone #0 (3 cones) or cone #1 (2 cones)

The timescale of motion on cone #2 is arbitrary. It can be fast or slow. For characterizing the complete motional process one has to supply cone and jump angles as well as the number of sites for all cones. In addition you have to specify the reative orientations of the different coordinate systems by supplying the euler angles αk, corresponding to the azimutal polar angles of zk+1 in the xkykzk - axes system.