Analytical energy gradient of the ground, excited, ionized and electron-attached states calculated by the SAC/SAC-CI method

The method of calculating the analytical energy gradients for the ground, excited, ionized and electron-attached states calculated by the SAC (symmetry adapted cluster)/SAC-CI (configuration interaction) method is formulated and implemented. It is adapted with the configuration selection procedure used in the SAC/SAC-CI method. The performance of the method is investigated for the Li2 and CO molecules.