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  • 1
    Electronic Resource
    Electronic Resource
    Erratum: "Density functional solvation model based on CM2 atomic charges" [J. Chem. Phys. 109, 9117 (1998); 111, 5624 (E) (1999)] (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 3930-3930 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1286968
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  • 2
    Electronic Resource
    Electronic Resource
    Accurate dipole moments from Hartree–Fock calculations by means of class IV charges (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 885-892 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Charge Model 2 (CM2) is parameterized for Hartree–Fock calculations with the correlation-consistent polarized valence double zeta (cc-pVDZ) basis set. The resulting charge model has an RMS error of 0.18 D over a training set of 198 polar molecules. The charge model is additionally applied to 8 nucleic acid bases and methyl azide to test its performance for nitrogen-containing compounds not found in the training set. The results demonstrate that this new CM2 model based on ab initio Hartree–Fock calculations is robust in predicting the charge distributions of such molecules. Comparison of CM2 results for the nitrogen-containing test set with those from a previous charge model, charge model 1 (CM1) based on AM1 (Austin model 1) and PM3 (parameterized model 3) wave functions, indicate that the CM2 charges are more accurate than those from the previous model. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479199
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  • 3
    Electronic Resource
    Electronic Resource
    Erratum: "Density functional solvation model based on CM2 atomic charges" [J. Chem. Phys. 109, 9117 (1998)] (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 5624-5624 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479820
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  • 4
    Electronic Resource
    Electronic Resource
    A class IV charge model for molecular excited states (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 724-733 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a new parameterization for calculating class IV charges for molecules containing H, C, N, O, F, Si, P, S, Cl, Br, and I from wave functions calculated at the intermediate-neglect-ofdifferential-overlap-for-spectroscopy (INDO/S) level. First we readjust the oxygen parameters in INDO/S on the basis of electronic excitation energies; this yields a new set of parameters called INDO/S2. Then we parameterize the charge model. The new model, called charge model 2 for INDO/S2 (CM2/INDO/S2), is parameterized against the most accurate available data from both ab initio and experimental sources for dipole moments of ground and excited electronic states. For a training set containing 211 dipole moments of molecules in their ground states and 33 dipole moments of molecules in their first excited states, the CM2/INDO/S2 model leads to a root-mean-square (rms) error in dipole moments of 0.26 D for ground states and 0.40 D for the excited states. The new model, INDO/S2 with CM2, systematically improves the n→π* excitation energies and the dipole moments of the excited states of carbonyl compounds. We also parameterized a CM2 model for the standard INDO/S model (CM2/INDO/S), which predicts quite accurate dipole moments for ground states with an rms error of 0.24 D. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478180
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  • 5
    Electronic Resource
    Electronic Resource
    Analytical energy gradients of a self-consistent reaction-field solvation model based on CM2 atomic charges (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 5503-5513 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Analytical energy gradients have been derived for an SM5-type solvation model based on Hartree–Fock self-consistent reaction-field theory and CM2 atomic charges. The method is combined with an analytic treatment of the first derivatives of nonelectrostatic first-solvation-shell contributions to the free energy and implemented in the General Atomic and Molecular Electronic Structure System (GAMESS). The resulting equations allow one to use accurate class IV charges to calculate equilibrium geometries of solutes in liquid-phase solutions. The algorithm is illustrated by calculations of optimized geometries and solvation free energies for water, methanol, dimethyl disulfide, and 9-methyladenine in water and 1-octanol. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478447
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  • 6
    Electronic Resource
    Electronic Resource
    Erratum: "A class IV charge model for molecular excited states" [J. Chem. Phys. 110, 724 (1999)] (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 5624-5624 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479828
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  • 7
    Electronic Resource
    Electronic Resource
    Density functional solvation model based on CM2 atomic charges (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 9117-9133 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We extend the SM5 solvation model for calculating solvation free energies of a variety of organic solutes in both aqueous and organic solvents so that it can be employed in conjunction with high-level electronic structure calculations. The extension is illustrated by presenting three implementations based on density-functional theory (DFT). The three implementations are called SM5.42R/BPW91/MIDI!6D, SM5.42R/BPW91/DZVP, and SM5.42R/BPW91/6-31G*. They have the following features: (1) They utilize gradient-corrected DFT with polarized double zeta basis sets to describe the electronic structure of a solute. The particular exchange-correlation functional adopted is Becke's exchange with the Perdew–Wang 1991 correlation functional, usually called BPW91. The MIDI!6D, DZVP, and 6-31G* basis sets are used. (2) They employ fixed solute geometries in solvation calculations. The model is designed to predict solvation free energies based on any reasonably accurate gas-phase solute geometry. (3) The electric polarization in the solute-solvent system is described by the generalized Born approximation with self-consistent reaction-field solute partial atomic charges obtained from the CM2 class IV charge model. (4) The solvation effects within the first solvation shell are included in the form of SM5-type atomic surface tensions. Both DFT parameterizations are developed using 275 neutral solutes and 49 ions with gas-phase Hartree–Fock/MIDI! geometries. These solutes contain a wide variety of organic functional groups which include H, C, N, O, F, P, S, Cl, Br, and I atoms. For 2135 free energies of solvation of the neutral molecules in water and 90 organic solvents, SM5.42R/BPW91/MIDI!6D, SM5.42R/BPW91/DZVP, and SM5.42R/BPW91/6-31G* yield mean unsigned errors in solvation free energies of 0.45 kcal/mol, 0.44 kcal/mol, and 0.43 kcal/mol, respectively. For 49 ions in water, SM5.42R/BPW91/MIDI!6D produces a mean unsigned error of 3.9 kcal/mol, while SM5.42R/BPW91/DZVP and SM5.42R/BPW91/6-31G* give 3.6 kcal/mol and 3.9 kcal/mol, respectively. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476521
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  • 8
    Electronic Resource
    Electronic Resource
    Extension of the platform of applicability of the SM5.42R universal solvation model (1999)
    Springer
    Theoretical chemistry accounts 103 (1999), S. 9-63 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract. We present eight new parameterizations of the SM5.42R solvation model: in particular we present parameterizations for HF/MIDI!, HF/6-31G*, HF/6-31+G*, HF/cc-pVDZ, AM1, PM3, BPW91/MIDI!, and B3LYP/MIDI!. Two of the new cases are parameterized using the reaction-field operator presented previously, and six of the new cases are parameterized with a simplified reaction-field operator; results obtained by the two methods are compared for selected examples. For a training set of 2135 data for 275 neutral solutes containing H, C, N, O, F, S, P, Cl, Br, and I in 91 solvents (water and 90 nonaqueous solvents), seven of the eight new parameterizations give mean unsigned errors in the range 0.43–0.46 kcal/mol, and the eighth – for a basis set containing diffuse functions – gives a mean unsigned error of 0.53 kcal/mol. The mean unsigned error for 49 ionic solutes (containing the same elements) in water is 3.5–3.9 kcal/mol for the Hartree–Fock, Becke–Perdew–Wang-1991 and Becke three-parameter Lee–Yang–Parr cases and 4.1 and 4.0 kcal/mol for parameterized model 3 and Austin model 1, respectively. The methods are tested for sensitivity of solvation free energies to geometry and for predicting partition coefficients of carbonates, which were not included in the training set.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002140050513
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  • 9
    Electronic Resource
    Electronic Resource
    Graphical representation of a new algorithm for nonorthogonalab initio valence bond calculations (1996)
    Springer
    Theoretical chemistry accounts 93 (1996), S. 35-48 
    Details
    ISSN: 1432-2234
    Keywords: VB method ; N! problem ; Group-theoretical approach ; VBSCF calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A pictorial representation of the algorithm using successive expansion method for the nonorthogonal VB calculations is given. With the help of this representation and the graph analysis, the efficiency of this algorithm is improved and theN! problem is reduced by a factor of about (N!)1/2. Anab initio VB program for valence bond self-consistent-field (VBSCF) calculations has been implemented based on this algorithm. Some VBSCF calculations have been performed for systems of up to 14 electrons. The statistics of the CPU time of the calculations indicate that this new group-theoretical approach is quite practical.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01113856
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  • 10
    Electronic Resource
    Electronic Resource
    MIDI! basis set for silicon, bromine, and iodine (1998)
    Springer
    Theoretical chemistry accounts 99 (1998), S. 192-196 
    Details
    ISSN: 1432-2234
    Keywords: Key words: Basis functions ; Bond angle ; Bond length ; Charges ; partial atomic ; d polarization functions ; Dipole moment ?tpb=-3.5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract. The MIDI! basis set is extended to three new atoms: silicon, bromine, and iodine. The basis functions for these heteroatoms are developed from the standard 3-21G basis set by adding one Gaussian-type d subshell to each Si, Br, or I atom. The exponents of the d functions are optimized to minimize errors in the geometries and charge distributions that these basis functions yield when they are used in Hartree-Fock calculations with all atoms represented by the MIDI! basis. The MIDI! basis is defined to use five spherical d functions in a d subshell. We present a detailed comparison of such calculations to calculations employing six Cartesian d functions in each d subshell; these studies show that 5D and 6D options give very similar results for molecular geometries and dipole moments, not only for compounds containing Si, Br, and I but also for compounds containing N, O, F, P, S, and Cl. The MIDI! basis set is also tested successfully for hypervalent Si compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002140050323
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