“…Therefore, from Eq. (18), the elastic energy of the lattice can be expressed as U (m,n) lat (a, b * ) and therefore can be represented as the following quadratic form in a and b * U (m,n) lat (a, b * ) = 2 a · H [1] k, k, k a + 2 a · mH [2] k, k, k + nH [3] k, k, k + H [4] k, k, k b * + 2 b * · m 2 H [5] k, k, k + n 2 H [6] k, k, k + m nH [7] k, k, k + mH [8] k, k, k + +nH [9] k, k, k + H [10]…”