  The equation of state for the beta stable nuclear matter is calculated
numerically, and then the Tolman-Oppenheimer-Volkov equation for the structure
of the neutron star is solved in the fourth-order Runge-Kutta algorithm. It
shows the mass and radius of the neutron star are functions of the central
density of the neutron star and a maximum mass of 1.932 solar masses with a
corresponding radius of 9.340km is obtained. Considering the equation of state
of the nuclear matter must obey the causality, a new factor c is added in the
nuclear potential energy formula. Therefore, with a new equation of state for
the beta stable nuclear matter when c=0.15, a new maximum mass of 1.440 solar
masses with a radius of 9.765km for the neutron star is obtained. Finally, the
contribution of the cosmological constant to the structure of the neutron star
is discussed, and we find the cosmological constant has minimal or negligible
influence on the properties of the neutron star.
