How can I use the Intrinsic Reaction Coordinate (IRC) proceudre?
Full Spartan can generate a reaction path using three approaches. The simplest is via the ‘energy profile’ calculation, which changes specific coordinates. (See the discusion of energy profile.) This works well for simple systems when the reaction coordinate can be well represented as internal coordinates (such as bond distance). A reaction path can also be generated by the calculation of the Transition State Geometry along with a frequency calculation. A list file can be generated for the signle imaginary frequency corresponding to the reaction coordinate. Spartan has also implemented a reaction coordinate algorithm to generate a reaction path given a transition state using the algorithm by Schmidt. (M.W. Schmidt, M.S. Gordon, M. Dupuis, J. Am. Chem. Soc. (1985), 107, 2585) This can be specified by checking the IRC button when performing a transition state geometry calculation. When selected, a new file will be generated that contains the reaction path. The IRC calculations are time c
