![]() We have just recently begun to learn how it can be used to enhance student understanding of the principles of crystallography and appreciation of the beauty of symmetry. The Jmol molecular visualization applet ( Jmol, 2010 ) is leading the way in this shift. The shift is away from licensed profit-driven software with periodic updates to openly available software with rapid community-based `immediate' development goals. The paradigm shift of the 21st century is away from monolithic programs that are designed to do a specific task on a specific platform in a specific subdiscipline of science and toward tools that are more modular, flexible and useful in a broad interdisciplinary context. These programs – web-based, open-source and platform-independent – combine features of rapid development, expert communities and widely accessible databases with the power of the web to communicate features of molecular and crystallographic structure in creative and artistic ways that could not have been imagined in 1965. This paper focuses on a new paradigm of computer program that aims to revolutionize the area of visualization in chemical education again, particularly in the area of crystallography. In addition, specialized software and web-based tutorials specifically targeting fundamental concepts of crystallography and molecular symmetry are now available (Cass & Rzepa, 2005 Harwood & Korkmaz, 2005 Johnston, 2005, 2008 Charistos et al., 2005 Kastner et al., 2000 ). While developed primarily for research purposes, these programs have found utility in the area of education as well, as noted in recent symposia at national American Chemical Society meetings (Kantardjieff, 2005 Battle et al., 2009 ). Since then, personal computing power has increased immensely, and a number of computer programs have been introduced that allow real-time interactive construction of crystals ( CrystalMaker, 2009 Shape, 2009 ) and exploration of molecular structure and bonding in the context of databases. The introduction of ORTEP (Johnson, 1965 ) over 40 years ago made possible for the first time a ready two-dimensional projection of the three-dimensional atomic world of crystals and ushered in a revolution in molecular visualization. It goes without saying that visualization is important in the area of crystallography. Introduction – crystallographic visualization Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Contract No. The XYZ renderings are based on Jmol: an open-source Java viewer for chemical structures in 3D. The molecule images are rendered by Indigo-depict. The find function is based on the complete Species Dictionary entries for the appropriate version of the ATcT TN. The reorganization of the website was developed and implemented by David H. Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.000 5 kJ/mol. The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic ). The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc. Uncertainty Quantification in Thermochemistry, Benchmarking Electronic Structure Computations, and Active Thermochemical Tables. (part of 2017 PCCP Hot Articles collection) Ng,Ī Vacuum Ultraviolet laser Pulsed Field Ionization-Photoion Study of Methane (CH4): Determination of the Appearance Energy of Methylium From Methane with Unprecedented Precision and the Resulting Impact on the Bond Dissociation Energies of CH4 and CH4+. Thermal Decomposition of Potential Ester Biofuels, Part I: Methyl Acetate and Methyl Butanoate. 1.122h of the Thermochemical Network (2020) available at ![]() Wagner,Īctive Thermochemical Tables: Thermochemistry for the 21 st Century.Īctive Thermochemical Tables (ATcT) values based on ver. ![]() Introduction to Active Thermochemical Tables: Several "Key" Enthalpies of Formation Revisited.ī. Note: The listed uncertainity of the reaction enthalpy is computed using the full covariance matrix.ī. Selected ATcT enthalpy of formation based on version 1.122h of the Thermochemical Network This version of ATcT results was generated from an expansion of version 1.122e to include results centered on the determination of the appearance energy of CH 3 + from CH 4.ĬH2(CH2CH2) (g) → H (g) + + (g)
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