  A new concept of the molecular structure optimization method based on quantum
dynamics computations is presented. Nuclei are treated as quantum mechanical
particles, as are electrons, and the many-body wave function of the system is
optimized by the imaginary time evolution method. A demonstration with a
2-dimensional H$^+_2$ molecule shows that the optimized nuclear positions can
be specified with a small number of observations. This method is considered to
be suitable for quantum computers, the development of which will realize its
application as a powerful method.
