MODEL OF A DISCLINATION CORE IN NEMATICS

The core structure of a disclination line of strength fl in uniaxial n ematics is determined by using a space-dependent mean-field approach s omehow based on the rod-like molecular model. It is shown that, due to distortion, biaxiality arises at all points of the defect core, excep t at the centre line where symmetry dictates uniaxiality; the orientat ional distribution of the rod-like molecules is there 'oblate', howeve r. Although, as is well known, the configuration of a fl defect is sta ble only under limiting conditions (as compared with either escaping i n the axial direction or splitting into two 1/2 lines), the simple exa mple developed here is indicative of a method which can readily be ext ended to more realistic, if mathematically more complex, situations su ch as +/- 1/2 lines, layers close to solid boundaries, etc.