摘要

For classical Hamiltonian with general form H = 1/2 Sigma(ij)M(ij)p(i)p(j) + 1/2 Sigma(ij)L(ij)q(i)q(j) we find a new convenient way to obtain its normal coordinates, namely, let H be quantised and then employ the invariant eigen-operator (IEO) method (Fan et at 2004 Phys. Lett. A 321 75) to derive them. The general matrix equation, which relies on M and L, for obtaining the normal coordinates of H is derived.