Is the Group Velocity Double the Phase Velocity at Low Velocities?

[RANDHIR SINGH]

At low velocity the group velocity is double the phase velocity (velocity of de Broglie waves). But phase velocity is more than the speed of light and group velocity is the velocity of particle. This means that particle velocity is also more than speed of light. But This seems to violate the postulate of relativity. Can anybody help to solve this paradoxical observation?

 

[cesiumfrog]

At low velocity the group velocity is double the phase velocity

Please cite your sources.