INDO Calculations on Electronic Structure and Spectra of Nitro Alkanes

Using the INDO method of Salahub and Sandorfy and the bonding parameters of the RINDO method after slightly modifying the weighting factor, the electronic spectra of nitro-alkanes in particular nitro-methane, nitro-ethane, nitro-propane and nitro-butane, were calculated after including lowest thirty singly excited Hartree-Fock states in the Configuration Interaction (CI) process. The results are in good agreement with experiment. The semi empirical self consistent field (SCF) methods, namely the CNDO and the INDO, developed by Pople and co-workers have long been used to study the electronic structure and spectra organic and inorganic molecules. To calculate the atomic co-ordinates, the program PROXYZ, obtained from the QCPE, USA and made available to us by Prof. G.Govil of the TIFR, Bombay was used. The plane containing the NO2 group was taken as the XZ plane.