Abstract
We developed a computer program MOLCAT to visualize results of vibrational analysis calculation. This program can treat Z-matrix used in ab initio molecular orbital calculation, and shows the vibrational mode as arrows with the molecular structure. We applied this program to show transition vectors of the intramolecular inversion of ammonia and the water exchange reaction of hexaaquacalcium(II). We are preparing to distribute MOLCAT as a free software.