where 1 D @2=@x2 C @2=@y2;3 D @=@x C i@=@y, and the overbar indicates the complex
conjugate value. .u; ;w/T and 8 are displacement vector and electric potential, respectively.
cij; "ij, and eij are the elastic, dielectric, and piezoelectric constants, respectively. The general
solution of (1) obtained by Ding et al. (1997) can be also rewritten in the following form: