def b2(self): """2D reciprocal lattice vector :math:`\\mathbf{b}_2=\\mathbf{b}^{*}`. """ a1 = Vector() a1[:2] = self.a1 return zhat.cross(a1)[:2] / self.cell_area
def a2(self): """2D lattice vector :math:`\\mathbf{a}_2=\\mathbf{b}`.""" b1 = Vector() b1[:2] = self.b1 return zhat.cross(b1) / self.cell_area