step toward a geometry of lower energy For additional details about how such geometry optimization searches are performed within modern computational chemistry software see the background Material where this subject was treated in greater detail It often turns out that a molecule has more than one stable structure(isomer) for a given electronic state. Moreover, the geometries that pertain to stable structures of excited electronic state are different than those obtained for the ground state(because the orbital occupancy and thus the nature of the bonding is different). again using arginine an example, its ground electronic state also has the structure shown in Fig. 5. 2 as a stable isomer. Notice that this isomer and that shown earlier have the atoms linked together in identical manners, but in the second structure the a-amino group is involved in two hydrogen bonds while it is involved in only one in the former. In principle, the relative energies of these two geometrical isomers can be determined by solving the electronic Schrodinger equation while placing the constituent nuclei in the locations described in the two figures 66 step toward a geometry of lower energy. For additional details about how such geometry optimization searches are performed within modern computational chemistry software, see the Background Material where this subject was treated in greater detail. It often turns out that a molecule has more than one stable structure (isomer) for a given electronic state. Moreover, the geometries that pertain to stable structures of excited electronic state are different than those obtained for the ground state (because the orbital occupancy and thus the nature of the bonding is different). Again using arginine as an example, its ground electronic state also has the structure shown in Fig. 5.2 as a stable isomer. Notice that this isomer and that shown earlier have the atoms linked together in identical manners, but in the second structure the a-amino group is involved in two hydrogen bonds while it is involved in only one in the former. In principle, the relative energies of these two geometrical isomers can be determined by solving the electronic Schrödinger equation while placing the constituent nuclei in the locations described in the two figures