Collisions between molecules in the

Collisions between electrostatically trapped molecules in the J=0 state are theoretically investigated. Molecules in this state are advantageous for the evaporative cooling, because inelastic collision is impossible at ultra-low temperature. However, inelastic collision is more significant than elastic collision at high temperature, because the off-diagonal dipole matrix elements are much larger than the diagonal elements. The elastic and inelastic collision cross-sections are calculated under the condition that the collisional kinetic energy is larger than the energy gap between the rotational states. The dependencies of the collision cross-sections on the collisional kinetic energy and molecular constants are examined