Long Monte Carlo simulations of liquid water at 25° and 1 atm have been carried out to study the convergence characteristics of the calculations. The recently reported TIPS2 potential was employed with system sizes of 125 and 216 monomers. The enthalpy, volume and radial distribution functions converge rapidly and show little size dependence. However, the rates of convergence are much slower for the fluctuation properties and are in the order: heat capacity (Cp) ⪢ isothermal compressibility (ϰ) ⪢ coefficient of thermal expansion (α). In fact,the weak coupling of the enthalpy and volume allows only crude estimates for α. In addition, the estimation of statistical error bounds for the thermodynamic properties is analyzed. It is found that very long (2500-3500 k) simulations are needed to yield valid estimates of the errors for the enthalpy, volume and Cp , while the erros for ϰ and α would still be elusive.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAdditions and Corrections - Optimized Intermolecular Potential Functions for Amides and Peptides. Hydration of Amides.William Jorgensen and Carol SwensonCite this: J. Am. Chem. Soc. 1985, 107, 17, 5025Publication Date (Print):August 1, 1985Publication History Published online31 March 2004Published inissue 1 August 1985https://pubs.acs.org/doi/10.1021/ja00303a603https://doi.org/10.1021/ja00303a603research-articleACS PublicationsRequest reuse permissionsArticle Views35Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Review: Unter Bezugnahme auf 57 Publikationen werden die verschiedensten pericyclischen Reaktionen untersucht und in Tabellen zahlreiche Beispiele aufgeführt.
Graphene, carbon nanotubes, and fullerenes are of great interest due to their unique properties and diverse applications in biology, molecular electronics, and materials science. Therefore, there is demand for methods that can accurately model the interface between carbon surfaces and their environment. In this letter we compare results for complexes of water, potassium ion, and chloride ion with graphene, carbon nanotube, and fullerene surfaces using a standard non-polarizable force field (OPLS-AA), a polarizable force field (OPLS-AAP), DFT, and ab initio theory. For interactions with water, OPLS-AA with the TIP3P or TIP4P water models describes the interactions with benzene (C(6)H(6)) and coronene (C(24)H(12)) well; however, for acenes larger than circumcoronene (C(54)H(18)) and especially for C(60), the interaction energies are somewhat too weak and polarization is needed. For ions interacting with carbon surfaces, inclusion of polarization is essential, and OPLS-AAP is found to perform well in comparison to the highest-level quantum mechanical methods. Overall, OPLS-AAP provides an accurate and computationally efficient force field for modeling condensed-phase systems featuring carbon surfaces.
No abstract is provided for this article.
The diffusion constant of TIP5P [J. Chem. Phys. 112, 8910 (2000)], the recently developed five-site rigid nonpolarizable model of liquid water that significantly improves the description of water’s density anomaly, has been calculated at a range of temperatures between −25 °C and 75 °C and pressures between 1 atm and 3000 atm. The diffusion constant, in units of 10−5 cm2/s, for TIP5P water at 25 °C and 1 atm is 2.62±0.04 as compared with the experimental value of 2.30. This is a significant improvement over most commonly used water models, e.g., for TIP4P and TIP3P [J. Chem. Phys. 79, 926 (1983)] the diffusion constants are 3.29±0.05 and 5.06±0.09, respectively, and for SPC it is 3.85±0.09. The diffusion constant of TIP5P decreases dramatically with decreasing temperature, as is observed experimentally, and the change in the diffusion constant as pressure is increased is also consistent with experimental results.
No abstract is provided for this article.
No abstract is provided for this article.
Since 1979 the city of Boulder, Colorado, has been involved in upgrading the city's street maintenance program. This work has involved improving staff maintenance procedures and identifying maintenance activities that, from a cost-effectiveness standpoint, can be contracted instead of completed inhouse. Based on a specific cost, skill, and equipment capability analysis, it was decided by the city that some maintenance activities would be done in-house, and a portion of other maintenance tasks would be done in-house and other portions for tasks such as snowplowing, permanent asphalt patching, and median mowing and maintenance would be contracted. There was also a decision to contract certain maintenance tasks, such as major street repair and street overlays, with no work on the task being done in-house. The program that was developed has resulted in a 35 percent reduction in permanent staff, from 27 to 19. Approximately 30 percent of the maintenance budget is now spent on contract maintenance. This maintenance process has enabled the city to improve its overall management of maintenance. In the past personnel, equipment, and material were usually used to do catchup, short-term repair work. Now maintenance is systematic, and more of the budget is spent on permanent repairs instead of on patching.
Ein nützliches Werkzeug für das Design von Liganden für Biorezeptoren ist die hier vorgestellte Kombination aus Monte‐Carlo‐Simulationen und Gibbs‐Energie‐Störungsrechnungen. Dies zeigt die gute Reproduktion experimenteller Befunde zur Wechselwirkung zwischen Cyclosporin A und Humancyclophilin mit den rechts angegebenen Cyclen. L = Ligand, P = Protein, h = „Loch”︁ (Verkleinerung eines Aminosäurerests), b = „Höcker”︁ (Vergrößerung eines Aminosäurerests). magnified image
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCis-trans energy difference for the peptide bond in the gas phase and in aqueous solutionWilliam L. Jorgensen and Jiali. GaoCite this: J. Am. Chem. Soc. 1988, 110, 13, 4212–4216Publication Date (Print):June 1, 1988Publication History Published online1 May 2002Published inissue 1 June 1988https://pubs.acs.org/doi/10.1021/ja00221a020https://doi.org/10.1021/ja00221a020research-articleACS PublicationsRequest reuse permissionsArticle Views1401Altmetric-Citations197LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of hydration on the structure of an SN2 transition stateWilliam L. Jorgensen and J. Kathleen BucknerCite this: J. Phys. Chem. 1986, 90, 19, 4651–4654Publication Date (Print):September 1, 1986Publication History Published online1 May 2002Published inissue 1 September 1986https://pubs.acs.org/doi/10.1021/j100410a037https://doi.org/10.1021/j100410a037research-articleACS PublicationsRequest reuse permissionsArticle Views209Altmetric-Citations35LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts
