Various computer-aided methods are used to estimate chemical structures from infrared spectra: an inductive method using a spectral database, an empirical method using a knowledge base, and a theoretical method using computational chemistry. With an aim to increase an ability for estimating structures from infrared spectra, various computer methods were intensively investigated. At first an inductive method using a spectral database was studied, and several problems were pointed out. Next a linear learning machine and a neural network were applied to estimating functional groups from infrared spectra as an empirical method, and several problems were also mentioned. Third a non-empirical molecular orbital calculation as a theoretical method was applied to examine the agreement between calculated and experimental vibrational frequencies and infrared intensities, and several problems were also underlined. It was concluded that there are many difficulties in estimating chemical structures from infrared spectra with the power of existing computers.

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A new computational chemistry environment (Facio) for PC GAMESS has been developed. In the environment, molecular modeling, preparation of GAMESS input file, execution of GAMESS calculation and visualization of the results are facilitated with GUI (graphic user interface). Molecular models are displayed as fine 3D graphics based on OpenGL technology. Molecular modeling features are compared to those of commercially available softwares. Isovalue surface of molecular orbitals, total electron density and electrostatic potentials are viewed as mesh surface. IR/Raman intensities are represented as simulated spectra and normal modes of vibrations are shown as animated graphics. All the features needed for computational chemistry are integrated in this software.
Besides the above functions, Facio can make models of polypeptides or polynucleotides with collaboration with Tinker, the molecular mechanics and dynamics package and can make a molecular surface with the help of MSMS, the software for the calculation of solvent-excluded surface. Further, it can serve as PDB file viewer for biopolymers, such as protein and nucleic acid, since the native molecular format of Facio is PDB (protein data bank).

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