| | 1 | Author
| J.M M Cordeiro | Requires cookie* | | | Title
| Effective Pair Potentials and Structure of Water  | | | | Abstract
| Classical Monte Carlo calculations have been performed in order to investigate the ability of the TIP4P, SPC, and SPCE water models to reproduce the structural features of liquid water. The simula-tions were carried out in the NPT ensemble at 4 thermodynamic conditions. The results are compared with recent neutron diffraction data. Essentially, the three models capture equally well the thermody-namic and structural features of water. Although they were parametrized to reproduce the water prop-erties at ambient conditions, the agreement with the experimental pair correlation functions was even better at supercritical conditions. This is because the effective pair potentials have some difficulty to re-produce cooperative interactions, like hydrogen bonds. These interactions are less effective at super-critical conditions, where the liquid behaves roughly like a gas | | | |
Reference
| Z. Naturforsch. 54a, 311—316 (1999); received December 16 1998 | | | |
Published
| 1999 | | | |
Keywords
| Monte Carle Simulation, Non-polarizable Water Models, Radial Distribution Functions, Hydrogen-bonds | | | |
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| default:Reihe_A/54/ZNA-1999-54a-0311.pdf | | | | Identifier
| ZNA-1999-54a-0311 | | | | Volume
| 54 | |
| 2 | Author
| Takahiro Ueda, Shigenori Nagatomo, Hirotsugu Masui, Nobuo Nakamura, Shigenobu Hayashi | Requires cookie* | | | Title
| Hydrogen Bonds in Crystalline Imidazoles Studied by 15 N NMR and ab initio MO Calculations | | | | Abstract
| Intermolecular hydrogen bonds of the type N-H...N in crystals of imidazole and its 4-substituted and 4,5-disubstituted derivatives were studied by 15 N CP/MAS NMR and an ab initio molecular orbital (MO) calculation. In the 15 N CP/MAS NMR spectrum of each of the imidazole derivatives, two peaks due to the two different functional groups, >NH and =N-, were observed. The value of the I 5 N isotrop-ic chemical shift for each nitrogen atom depends on both the length of the intermolecular hydrogen bond and the kind of the substituent or substituents. It was found that the difference between the experimen-tal chemical shifts of >NH and =N-varies predominantly with the hydrogen bond length but does not show any systematic dependence on the kind of substituent. The ab initio MO calculations suggest that the hydrogen bond formation influences the 15 N isotropic chemical shift predominantly, and that the difference between the 15 N isotropic chemical shift of >NH and =N-varies linearly with the hydrogen bond length. | | | |
Reference
| Z. Naturforsch. 54a, 437—442 (1999); received March 31 1999 | | | |
Published
| 1999 | | | |
Keywords
| 15 N CP/MAS NMR, Imidazoles, Hydrogen Bond, 15 N Chemical Shift, ab initio MO Calculation | | | |
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| default:Reihe_A/54/ZNA-1999-54a-0437.pdf | | | | Identifier
| ZNA-1999-54a-0437 | | | | Volume
| 54 | |
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