In warm dense matter(WDM),the thermal motion energy of a nucleus may be comparable to its coupling energy with the neighbor nuclei and comparable to the valence electronic orbital motion energy.The atoms are so close to each other that they interact strongly in the whole time of nuclear motion and there are significant thermal fluctuations in electron orbitals accompanied with the thermal motion of the nuclei.As the much small mass of electrons,the fluctuations of the electron orbitals are almost adiabatic dynamical changes with nuclear motion.