MOPAC/ZINDO

The suite of CAChe packages can run entirely on Windows or on Macintosh, while the compute engines (e.g MOPAC, ZINDO, DGauss) can also be run remotely on a networked SGI UNIX GroupServer. 

For a more detailed analysis of the absorption properties, the UV spectrum of the model compound (Scheme 7), which was also synthesized, was calculated using semiempirical methods (MOPAC/ZINDO). The experimental UV spectrum of the model compound is nearly identical to the spectrum of the polymer. From the calculation it was derived that four UV transitions contributed to the absorption maximum at 330 nm. In detail, these are the HOMO LUMO, the HOMO->LUMO+l, the HOMO LUMO+2, and the HOMO—LUMO+3 transitions. The first two orbital excitations showed a large involvement of the triazene group, whereas the other two are mainly localized at the phenyl moieties. Similar results were previously reported for aryl dialkyl triazenes [119, 184] which have the same structural unit. Starting from simple chemical considerations, it could be thought that the number of chromophores responsible for the absorbance at around 300 nm is a low value, for example 2 or 4 per unit. On the other hand, the semiempirical calculations indicated the involvement of the phenyl moieties in the absorption properties therefore, the chromophore number in the calculation was not restricted to low values. As a starting point for the calculation, numbers close to the expected value were chosen. 

In Sections 11.2 and 11.3, highly sensitive detection mechanisms involving bromate formation and chemiluminescence were quantitatively analyzed using computational chemical methods. In the case of bromate, the MOPAC/ZINDO in CAChe programs were used to calculate spectra, while in the case of chemiluminescence, a MOPAC/PM5 program was used to calculate ape values as indicators of electron localization. 

Quantum CAChe allows chemists to predict and visualize chemical structures, properties, and reactivity. With its experiment-driven approach. Quantum CAChe focuses on chemical properties and results, allowing the user to concentrate on chemistry rather than computer techniques. Quantum CAChe is a stand-alone package running under Windows95/NT, and includes all the components of Personal CAChe plus local MOPAC, ZINDO, and MD. More demanding calculations can be run remotely using CAChe GroupServer. 

This method has been used extensively in the literature for the calculation of molecular hyperpolarizabilities. The calculations employed here utilized the MOPAC and ZINDO methods within the 4.0.1 CAChe Worksystem (Oxford Molecular) software package. MNDO-AM1 method and parameterization M. J. S. Dewar and M. L. McKee, J. Am. Chem. Soc., 1977, 99, 5231. Oscillator strengths were calculated using the ZINDO method. 

Figure 12 Number of publications per year in the CJACS file mentioning semiem-pirical MO programs MOPAC, AMPAC, AMSOL, or ZINDO. The search queries for each curve were (1) mopac, (2) ampac, (3) amsol, and (4) zindo.

Graphical pre- and postprocessor for semiempirical molecular orbital programs extended Hiickel, MOPAC, and ZINDO. Structure building from library of fragments and molecules manipulation. Stick, ball-and-stick, and space-filling display. Orbital, electron density, and electrostatic maps. Reaction energy surfaces. IR and UV spectra. MM2 energy minimization. Dynamics. 

The SINDOl program is less generally available than either AMPAC, MOPAC, or ZINDO, but a considerable amount of literature using this method is beginning to appear. The model, as described above, has been parameterized on experimental geometries, binding energies, dipole moments, and ionization potentials. Many comparisons between SINDOl and MINDO/3 and MNDO appear, and we reproduce some of these comparisons in Tables 5 and 6. 

If the reaction path is not obvious, then the most general techniques require information about the second derivatives. There exist, however, several often successful techniques that do not require this. The MOPAC and AMPAC series of programs utilize, for example, the saddlepoint technique, which attempts to approach the transition state from the reactant and product geometry simultaneously. The ZINDO set of models can utilize a combination of augmented Hessian and analytic geometry techniques. This is a very effective method, but unfortunately the augmented Hessian method does require approximate second derivatives and is somewhat time consuming. 

Computational chemistry, which can predict the spectra of a variety of compounds that cannot be obtained in their pure form, was used to study the highly sensitive detection of bromate in ion chromatography. Several possible ions, molecules and their complexes were constructed by a molecular editor, and optimized by MM2 and MOPAC (PM3) calculations. Their possible electronic spectra were then obtained by the Zerner s Intermediate Neglect of Differential Overlap (ZINDO) (INDO)-Visualyzer in the CAChe program. The Amax of the spectra and the transition dipoles were calculated using the ProjectLeader program. Comparison of the experimental and predicted results indicated that Brs" was the probable reaction product, and that N02 and ClO accelerated the reaction. ... 

PM3 or MNDO hamiltonians for calculations on organic molecules. The MOPAC and AMPAC packages are the usual sourees for these programs. The exeited state spectrum calculated in the NDDO based methods is usually inferior to that obtained in CNDO(S) or ZINDO/INDO, but sealing is sometimes used to overcome this diffieulty. It is essential to use SDCI or better if any reasonable treatment of the y-hyperpolarizabiUty is to be achieved. 

MINDO/3, MNDO, MNDOC, SINDOl, CNDO/ ZINDO," AMI, and recently PM3, as mentioned before. Newcomers to die field should be aware that the program and the method it runs may have, but do not need to have, the same name. MOPAC, for example, will allow MlNDO/3, MNDO, AMI, and PM3 calculations to be run. 

The type and location of donor and acceptor groups on this chromophore that will maximize second order NLO properties is not obvious, however, because the ends of the cyanine chromophore are coordinated to the boron atom and therefore not available for direct modification. A noncentrosymmetric substitution pattern must provide for both a charge transfer transition that is related to the strong absorption in the symmetric molecule and a ground state dipole moment which is substantially parallel to this transition. Candidate structures were therefore evaluated computationally with MOPAC using the AM 1 basis for geometry optimization. Spectroscopic INDO/S methods with configuration interaction (ZINDO) were used for electronic spectra estimation (6). 

The first generally available implementation of COSMO was the MOPAC implementation in 1993. In this the matrix inversion algorithm has been used. The nonzero elements of the semiempirical density matrix are used for the density representation Q and the interaction of the density with the screening charges is expressed by the corresponding atom centered multipoles. This implementation follows the theory outlined above, closely. Several other semiempirical Implementations of COSMO have appeared meanwhile (MNDO, AMPAC, ZINDO) which closely follow the MOPAC/COSMO concept have appeared since (see MNDO). 

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