PM3 parametric method

PM3 parametric method 3 (semiempirical quantum chemical method)... 

In the late 1960s and early 1970s, Dewar and co-workers developed the modified INDO (MINDO) methods. In 1976, the modified neglect of diatomic overlap (MNDO) method " was introduced. Further refinements were made to MNDO and improved parametrizations, AMI Austin model 7) PM3 parametric method and PM5 parametric method 5), ... 

Modified Negiect of Diatomic Overlap, Parametric Method Number 3 (MNDO-PM3)... 

Various parameterizations of NDDO have been proposed. Among these are modified neglect of diatomic overlap (MNDO),152 Austin Model 1 (AMI),153 and parametric method number 3 (PM3),154 all of which often perform better than those based on INDO. The parameterizations in these methods are based on atomic and molecular data. All three methods include only valence s and p functions, which are taken as Slater-type orbitals. The difference in the methods is in how the core-core repulsions are treated. These methods involve at least 12 parameters per atom, of which some are obtained from experimental data and others by fitting to experimental data. The AMI, MNDO, and PM3 methods have been focused on ground state properties such as enthalpies of formation and geometries. One of the limitations of these methods is that they can be used only with molecules that have s and p valence electrons, although MNDO has been extended to d electrons, as mentioned below. 

Abstract Quantitative structure-activity relationship (QSAR) analysis for minimum inhibitory concentration (MIC) of phenothiazines and benzo[a]phenothiazines was investigated based on the theoretical calculations. Four different dipole moments (/jq, /xesp g, /zw, and /zesp-w) and heats of formation (AHf) of the phenothiazines [1-20], benzo [n]phenothiazines [21-29], and benz[c]acridines [30-41] were separately calculated in the gas-phase and the water-solution by the conductor-like screening model/parametric method 3 (COSMO/PM3) technique. The MIC values of phenothiazines [1-20] were well correlated to A AHf, HOMO energy and hq. QSAR may be applicable to predict the MIC of phenothiazines. 

Theoretical calculations. Molecular orbital calculations using parametric method 3 (PM3) were performed with application of the winMOPAC... 

PM3 Modified neglect of diatomic overlap, parametric method number 3 Pro Proline... 

Modified Neglect of Diatomic Overlap Parametric Method Number 3 (MNDO-PM3) 3.10.6 The MNDO/d Method 88 89 5.5 5.6 5.4.5 Correlation Consistent Basis Sets Extrapolation Procedures Isogyric and Isodesmic Reactions 162 164 169... 

The ground-state dipole moments of BPHTs were calculated by evaluating the vector sum of the it moment (computed by the Pariser-Parr-Pople (PPP) method) and the a moment (from cr-bond moments) [17], a separate set of dipole moment values being obtained by the parametric method 3 (PM3) ([25] and references therein) (Table 5). By comparison, the calculated ground-state dipole moment values were considerably lower than the experimental ones. In some cases, the agreement between the experimental and calculated ground-state dipole moments was rather poor [17]. 

Many popular semiempirical methods are based on the original MNDO method. The most prominent of these are Austin Model 1 (AMI) by Dewar et al. [73] and Parametric Method 3 (PM3) by Stewart [74], These three methods represent the semiempirical standard for the calculation of organic molecules and are included in popular program packages such as Gaussian [78], CERIUS [79], SPARTAN [80], MOP AC [81], and AMPAC [82], Recently, AM 1 and PM3 have also been extended for the treatment of transition metal compounds [75-77], In principle, they only differ in the parameterization and in the empirical function fAB [Eq. (42)]. 

PM3 Parametrized Model 3. PM3 is a version of the AMI method reparametrized by J.J. Stewart. On the whole PM3 gives better estimates of the heat of formation than AMI. 

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