We investigate the dynamic scaling behavior of ac conductivity () in three-dimensional ͑3D͒ unitary and symplectic systems in addition to orthogonal one by means of large-scale simulations. It is demonstrated that the ac conductivity near the Anderson transition behave as ()ϰ ␦ (␦Ӎ1/3) for all of the above systems. Numerical calculations are performed by an efficient algorithm based on the forced oscillator method ͑FOM͒, which enables us to accurately treat large-scale quantum systems with less computational effort. The values of the exponents ␦ are determined by the finite-time scaling method for the FOM. ͓S0163-1829͑99͒11943-X
