Hydration of small anions: Calculations by the AM1 semiempirical method

Davis, Larry P.; Burggraf, Larry W.; Storch, Donn M.

doi:10.1002/jcc.540120308

Cited by 5 publications

References 32 publications

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Solvation and Counterion‐Distribution of Sodium Octanoate Micelles Studied by Molecular Dynamics Simulations

Kühn

Rehage

1997

Ber Bunsenges Phys Chem

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In this publication we have studied molecular details of the solvent layer and the counterion distribution around sodium octanoate micelles. The results were obtained from computer experiments using molecular dynamics simulations. From the model it was possible to calculate the radial distribution functions, which give informations on the average distance between water molecules and the polar surfactant head groups. We observed different types of solvent layers. From these experiments it was also possible to calculate the number of hydrogen bonds between surrounding water molecules and the polar surfactant head groups. These results coincide well with experimental data and with other types of computer experiments. In analogy to water molecules it was also possible to get informations on the distribution of sodium counterions around the charged micelle. These results are in general agreement with experimental and theoretical data and they can be used to calculate Coulomb interactions and the net surface charge of the micellar aggregates.Ber. Bunsenges. PhI''\". Chem. 10/. /493-/500 (/997) No. /0

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Solvation and Counterion‐Distribution of Sodium Octanoate Micelles Studied by Molecular Dynamics Simulations

Kühn

Rehage

1997

Ber Bunsenges Phys Chem

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Ability of the PM3 quantum‐mechanical method to model intermolecular hydrogen bonding between neutral molecules

1993

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The PM3 semiempirical quantum-mechanical method was found to systematically describe intermolecular hydrogen bonding in small polar molecules. PM3 shows charge transfer from the donor to acceptor molecules on the order of 0.02-0.06 units of charge when strong hydrogen bonds are formed. The PM3 method is predictive; calculated hydrogen bond energies with an absolute magnitude greater than 2 kcal mol-' suggest that the global minimum is a hydrogen bonded complex; absolute energies less than 2 kcal mol-' imply that other van der Waals complexes are more stable. The geometries of the PM3 hydrogen bonded complexes agree with high-resolution spectroscopic observations, gas electron diffraction data, and high-level ab initio calculations. The main limitations in the PM3 method are the underestimation of hydrogen bond lengths by 0.1-0.2 for some systems and the underestimation of reliable experimental hydrogen bond energies by approximately 1-2 kcal mol-l. The PM3 method predicts that ammonia is a good hydrogen bond acceptor and a poor hydrogen donor when interacting with neutral molecules. Electronegativity differences between F, N, and 0 predict that donor strength follows the order F > 0 > N and acceptor strength follows the order N > 0 > F. In the calculations presented in this article, the PM3 method mirrors these electronegativity differences, predicting the F-H---N bond to be the strongest and the N-H---F bond the weakest. It appears that the PM3 Hamiltonian is able to model hydrogen bonding because of the reduction of two-center repulsive forces brought about by the parameterization of the Gaussian core-core interactions. The ability of the PM3 method to model intermolecular hydrogen bonding means reasonably accurate quantum-mechanical calculations can be applied to small biologic systems. 0 1993 by John Wiley & Sons, Inc.

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Geometries and Stabilities of G·GC, T·AT, A·AT an C·GC Nucleic Acid Base Triplets

Marino

Russo

Sarubbo

et al. 1997

Biomolecular Structure and Dynamics

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Hydration of small anions: Calculations by the AM1 semiempirical method

Cited by 5 publications

References 32 publications

Solvation and Counterion‐Distribution of Sodium Octanoate Micelles Studied by Molecular Dynamics Simulations

Solvation and Counterion‐Distribution of Sodium Octanoate Micelles Studied by Molecular Dynamics Simulations

Ability of the PM3 quantum‐mechanical method to model intermolecular hydrogen bonding between neutral molecules

Geometries and Stabilities of G·GC, T·AT, A·AT an C·GC Nucleic Acid Base Triplets

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