Extension of the Neglect of Diatomic Differential Overlap Method to Spectroscopy. NDDO-G Parametrization and Results for Organic Molecules

Abstract

A new semiempirical scheme, referred to as NDDO-G, for calculating geometries and spectroscopic properties of molecules, is described. The method is based on the NDDO (neglect of diatomic differential overlap) approximation. It uses the point-charge model and the Mataga−Nishimoto formula to evaluate two-center two-electron integrals. The NDDO-G model has been parametrized for the elements H, C, N, and O. Molecular geometries of organic molecules are well predicted by NDDO-G; for 60 molecules, the mean absolute error of bond lengths is 0.014 Å and that of bond angles is 1.9°. The spectroscopic variant of the NDDO-G scheme provides electronic excitations using configuration interaction of singly excited states (CIS). It has been applied to calculate absorption spectra (vertical transitions) of several dozens organic molecules and photoelectron spectra within Koopmans' approximation. These NDDO-G results are compared with experimental results and with results of high-level ab initio calculations. The mean absolute error of NDDO-G excitation energies is 0.13 eV = 1050 cm-1 (196 comparisons). First and several higher ionization potentials are reproduced with a mean absolute error of 0.24 eV (123 comparisons). The proposed method may be used for studying structures of large organic and biological molecules and for interpreting and predicting their absorption and photoelectron spectra. As an example, we discuss the spectroscopy of free-base porphin.

Quantum mechanical model for Maya Blue

“…The procedure is relatively simple and runs fast in modern computers even for molecules that are too big to be studied with first‐principle methods 31–33. Other known semiempirical procedures 34–38, currently used elsewhere for large systems, were developed after a heavy a posteriori parameterization to fit experimental results. In such large molecular systems the CNDOL/21 Hamiltonian allows an accurate variational optimization of excited states through Configuration Interaction of Singles (CIS) in a large active space 27.…”

Semiempirical local spin: Theory and implementation of the ZILSH method for predicting Heisenberg exchange constants of polynuclear transition metal complexes

“…The local spin formalism has been implemented in the ZINDO program 6 and can be used with either RHF or UHF wave functions computed with the semiempirical methods INDO/S 7, 9, 15, 16, INDO/1 7, 8, 16, AM1 32, MNDO 33, 34, PM3 35, 36, NDDO‐G 37, CNDO 38, 39, INDO 40, PPP 41–44, and extended Hückel 45–51. A wrapper subroutine was added to ZINDO that successively executes the program and computes local spin expectation values for a list of input files.…”

Parameter Calibration of Transition-Metal Elements for the Spin-Polarized Self-Consistent-Charge Density-Functional Tight-Binding (DFTB) Method: Sc, Ti, Fe, Co, and Ni

“…Efforts to reduce computational cost associated with quantum chemical calculations have led in last several decades to development of a large number of semiempirical methods, such as MNDO, 2 SINDO/1, 3 AM1, 4 PM3, 5 SAM1, 6 MNDO/d, 7 PM3/tm, 8 and NDDO-G, 9 which can routinely treat molecular systems containing up to a thousand or so atoms. An alternative approach to perform calculations for such large systems is an approximate density functional technique called the density functional tight-binding (DFTB) method.…”