A CLARIFICATION OF VIBRATIONAL HEAT CAPACITY OF DIATOMIC MOLECULES

In the ideal gas of diatomic molecules, the simplest coupling of vibrational motion and rotational motion inside the molecule makes the vibratory motion deviate from the equipartition theorem of energy. At this time, the contribution of vibrational degrees of freedom to energy is not necessarily kT. For hydrogen molecules, even if the temperature is close to the characteristic temperature of dissociation, the contribution of vibration degrees of freedom to energy is approximately kT, that is, the equipartition theorem holds.