the laser at larger distances from the nucleus. This is in contrast to the approximation made by neglecting the potential of the laser at regions near the nucleus. Perelomov et al. included the Coulomb interaction at larger internuclear distances. Their model (which is called the PPT model) was derived for short-range potential and includes the effect of the long-range Coulomb interaction through the first-order correction in the quasi-classical action. In the quasi-static limit, the PPT model approaches the ADK model. Many experiments have been carried out on the MPI of rare gas atoms using strong laser pulses, through measuring both the total ion yield and the kinetic energy of the electrons. Here, one only considers the experiments designed to measure the total ion yield. Among these experiments are those by Chin et al., Augst et al. and Auguste et al. Chin et al. used a 10.6 μm CO2 laser in their experiment. Due to the very small frequency of the laser, the tunneling is strictly quasi-static, a characteristic which is not easily attainable using pulses in the near infrared or visible region of frequencies. These findings weakened the suspicion on the applicability of models basically founded on the assumption of a structureless atom. Larochelle et al. have compared the theoretically predicted ion versus intensity curves of rare gas atoms interacting with a Ti:sapphire laser with experimental measurement. They have shown that the total ionization rate predicted by the PPT model fits very well the experimental ion yields for all rare gases in the intermediate regime of Keldysh parameter. Analytical formula for the rate of MPI ( be careful, there are a lot of typos in the following section ) The dynamics of the MPI can be described by finding the time evolution of the state of the atom which is described by the Schrödinger equation. The form of this equation in the electric field gauge, assuming the single active electron (SAE) approximation and using dipole approximation, is the following where is the electric field of the laser and is the static Coulomb potential of the atomic core at the position of the active electron. By finding the exact solution of equation (1) for a potential ( the magnitude of the ionization potential of the atom), the probability current is calculated. Then, the total MPI rate from short range potential for linear polarization, , is found from where is the frequency