A wave equation in the curl-free space is treated, and its weak solutions are constructed by use of a minimizing method. Numerical calculations are also done. Physical backgrounds are on equilibrium states of the smectics liquid crystal. Motion of zero points for the director vector is shown under control of an equation of wave type.
"A wave equation in the curl-free space related to a smectics liquid crystal." Differential Integral Equations 18 (1) 61 - 70, 2005.