Mean vibrational amplitudes of 1,3-butadiene, acrolein and glyoxal

The mean vibrational amplitudes of 1,3-butadiene, acrolein, and glyoxal have been calculated by explicitly including the effects of kinematic anharmonicity, and are compared with the corresponding amplitudes with this effect neglected. The scaled and unscaled quantum-mechanical force fields calculated at the correlated MP2/631G*//MP2/6-31G* computational level were used. The calculated results are also compared with the available experimental data.