Theoretical temperature-electric-field phase diagram for betaine calcium chloride dihydrate

Theoretical phase diagrams for betaine calcium chloride dihydrate in the presence of an external electric field are calculated. A phenomenological approach applied earlier by the present authors [J. Phys.: Condens. Matter 10, 1803 (1998)] for the construction of the temperature-pressure phase diagram, which is in agreement with the experimental diagram, is used. Expressions for thermodynamic potentials of different phases and for boundaries between these phases are given in an explicit or parametric form. The theoretical temperature-electric-field phase diagram is plotted and is compared with the experimental diagram.