INDO quantum chemical method

Three versions of Modified Intermediate Neglect of Differential Overlap (MINDO) models exist, MINDO/1, MINDO/2 and MINDO/3. The first two attempts at parameterizing INDO gave quite poor results, but MINDO/3, introduced in 1975, produced the first general purpose quantum chemical method which could successfully... 

As an alternative to ab initio methods, the semi-empirical quantum-chemical methods are fast and applicable for the calculation of molecular descriptors of long series of structurally complex and large molecules. Most of these methods have been developed within the mathematical framework of the molecular orbital theory (SCF MO), but use a number of simplifications and approximations in the computational procedure that reduce dramatically the computer time [6]. The most popular semi-empirical methods are Austin Model 1 (AMI) [7] and Parametric Model 3 (PM3) [8]. The results produced by different semi-empirical methods are generally not comparable, but they often do reproduce similar trends. For example, the electronic net charges calculated by the AMI, MNDO (modified neglect of diatomic overlap), and INDO (intermediate neglect of diatomic overlap) methods were found to be quite different in their absolute values, but were consistent in their trends. Intermediate between the ab initio and semi-empirical methods in terms of the demand in computational resources are algorithms based on density functional theory (DFT) [9]. 

Dynamic Response Functions. - The perturbation series formula or spectral representation of the response functions can be used only in connection with theories that incorporate experimental information relating to the excited states. Semi-empirical quantum chemical methods adapted for calculations of electronic excitation energies provide the basis for attempts at direct implementation of the sum over states (SOS) approach. There are numerous variants using the PPP,50,51 CNDO(S),52-55 INDO(S)56,57 and ZINDO58 levels of approximation. Extensive lists of publications will be found, for example, in references 5 and 34. The method has been much used in surveying the first hyperpolarizabilities of prospective optoelectronically applicable molecules, but is not a realistic starting point for quantitative calculation in un-parametrized calculations. 

Recent publications calculate the basicity of aromatic compounds and the electronic structure of the respective arenium ions by quantum chemical methods in different approximations — by semi-empirical methods MO LCAO (methylbenzenes " ), CNDO, CNDO/2 and CNDO/2FK (benzene " , toluene and other monoalkylbenzenes " , anisole , a series of monosubstituted benzoles , poly-methylbenzenes , monomethylnaphthalenes and polycyclic aromatic hydrocarbons ) INDO (benzene , cresols ) MINDO-2 and MINDO-3 (benzene , toluene ) by nonempirical (ab initio) methods using the basis... 

Quantum chemical methods were employed with variable success in theoretical studies of solvatochro-mism. Electronic transition energies of molecules in the gas phase may be calculated by ab-initio and semiempirical methods. The latter are more frequently used because of their much smaller computational cost and also because of the existence of programs, like CNDO/S and INDO/S, that were parametrized for spectral studies. Calculation of solvent effects poses a major problem in the prediction of solvatochromic shifts. Several methods exist that are based on a continuum model, where changes in the electronic levels of the molecule are treated as perturbations by the solvent dielectric constant. This model was extended to include the effect of an added salt. Alternatively, the bulk solvent may be replaced by point charges. ... 

The CEO computation of electronic structure starts with molecular geometry, optimized using standard quantum chemical methods, or obtained from experimental X-ray diffraction or NMR data. For excited-state calculations, we usually use the INDO/S semiempirical Hamiltonian model (Section IIA) generated by the ZINDO code " however, other model Hamiltonians may be employed as well. The next step is to calculate the Hartree— Fock (HE) ground state density matrix. This density matrix and the Hamiltonian are the Input Into the CEO calculation. Solving the TDHE equation of motion (Appendix A) Involves the diagonalization of the Liouville operator (Section IIB) which is efficiently performed using Kiylov-space techniques e.g., IDSMA (Appendix C), Lanczos (Appendix D), or... 

We present results of theoretical calculations based mainly on semiempirical (INDO) quantum chemical electronic structure calculations, and in one ease (Section 2.44.4.3), on large-scale MD simulations. The spectroscopic Hamiltonian (INDO/s) parametrized by Zemer and co-workers for systems including both organic and transition M-based moieties, is very useful for treating electronic properties of TMCs, including evaluation of Alternatively, the method... 

The geometry of nitronates has not been adequately studied by quantum-chemical calculations. For example, the bond lengths in nitronate Me2C=N(0)OMe were calculated by the INDO method for ideal geometry (248). 

Quantum chemical calculations by means of the CNDO/2 and INDO methods were carried out for the 4-oxo compound (198 R = H), for the isomeric 6-oxo compound, and for the 9a-hydroxy-substituted perhydro derivative.381... 

Several versions of modified INDO (MINDO) that employ such a parameterization have been proposed. These include MINDO/1, MINDO/2, MINDO/2, and MINDO/3, only the last of which resulted in a quantum chemical program that was widely used. MINDO/3151 is parameterized for H, B, C, N, O, F, Si, P, S, and Cl, although certain combinations of these atoms are not parameterized. The MINDO/3 method is no longer heavily used because the parameterized NDDO methods are generally more accurate. 

In connection with these earlier quantum chemical studies we had also extended the derivations of some of the semi-rigorous techniques [such as deriving the necessary expressions for including d orbitals in the INDO method (25)1 suggested procedures to improve other methods [how to improve the description of lone pairs in the PCILO method (26)1 and performed calculations by various techniques comparing the results of less rigorous calculations with our large basis set ab-initio calculations (27 >28). 

Zhou. Y.-F., Wang, X.-M, Zhao, X., Jiang, M,-H, A quantum-chemical INDO/CI method for calculating two-photon cross sections. J. Phys, Chem. Sol. 62, 1075—1079 (2001)... 

Quantum chemical calculations on the electronic spectrum of compounds are generally carried out by separate calculations on the ground state and on each excited state. Most of the initial calculations on thiophene have been carried out by the PPP method, although calculations by CNDO and INDO have also been done. Results obtained prior to 1981 are discussed in detail in the review by Henriksson-Enflo <85HC(44/l)215>. 

The study by Visser et al. impressively demonstrates that rigorous relativistic ab initio calculations can also be applied to investigate local phenomena in solids. However, keeping in mind the multiple sources of error in the representation of the wavefunction in the study by Visser et al. it is likely that results of a comparable quality could be obtained with simplified quantum-chemical schemes, e.g. the quasirelativistic PP approach or the INDO method. 

This latter model is extensively utilized by semiempirical schemes such as the Compete Neglect of Differential Overlap (CNDO), Intermediate Neglect of Differential Overlap (INDO), Neglect of Diatomic Differential Overlap (NDDO), etc. methods (called NDO-family, Pople Beveridge 1970) which represent the quantum chemical tools for studying the electronic structure of larger molecules which are not available for abinitio calculations. We shall not discuss the details of the parametrization of these schemes. The aim of this section is merely to put down the second quantized Hamiltonians of the most frequently used semiempirical methods of this type. ... 

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