Weblab supports spin-1/2 (<sup>1</sup>H, <sup>13</sup>C,..) and spin-1 systems (<sup>2</sup>H, <sup>13</sup>C-<sup>1</sup>H). The corresponding nmr-relevant interactions considered by Weblab are first order chemical shift, quadrupolar or heteronuclear dipole-dipole interaction. According to your selection, Weblab provides the proper menus and reasonable starting values for the interaction tensors.

When I=1/2, chemical shift is considered as interaction and the spectrum for a single transition is calculated. In the other case Weblab assumes quadrupolar coupling and produces a symmetric spectrum according to the two allowed transitions.