For a particular 2D problem, it is known that the Hamiltonian is separable in Cartesian co-ordinates (e.g. H^=H^x+H^y ) Considering separability alone, identify the function that could not be an eigenfunction of this operator over any domain. e(x+y)2 sin(nxx)sin(nyy) e(x2+y2) X(x)Y(y) x(ax)ey2a is a constant