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Quantum Chemistry Program Exchange
The Quantum Chemistry Program Exchange (QCPE) was an organization located at Indiana University Bloomington from 1963 to 2007 that was devoted to the distribution of computational chemistry software before electronic file transfer on the internet became a widely available method of software distribution. The QCPE was originally founded by Prof. Harrison Shull and was managed by Richard Counts for most of its existence. Financial support for the QCPE was originally provided by the Air Force Office of Scientific Research until 1969, and funding continued under an interim grant from the National Science Foundation in 1971 until it became financially self-sustaining in 1973. The QCPE maintained a catalog of software that expanded through regular contributions from chemistry software developers. New software contributions were announced through a quarterly QCPE Newsletter that were eventually formalized into a QCPE Bulletin in 1981, which allowed for software citations to numbered softw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indiana University Bloomington
Indiana University Bloomington (IU Bloomington, Indiana University, IU, IUB, or Indiana) is a public university, public research university in Bloomington, Indiana, United States. It is the flagship university, flagship campus of Indiana University and its largest campus, with over 48,000 students. Established as the state's seminary in 1820, the name was changed to "Indiana College" in 1829 and to "Indiana University" in 1838. Indiana University is a member of the Association of American Universities and is Carnegie Classification of Institutions of Higher Education, classified among "R1: Doctoral Universities – Very high research activity". Its schools and programs include the Jacobs School of Music, Kelley School of Business, Indiana University School of Education, School of Education, Indiana University School of Informatics, Luddy School of Informatics, O'Neill School of Public and Environmental Affairs, Indiana University School of Public Health-Bloomington, School of Pu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CNDO/2
Complete Neglect of Differential Overlap (CNDO) is one of the first semi empirical methods in quantum chemistry. It uses the ''frozen core approximation'', in which only the outer valence electrons are explicitly included, and the approximation of zero-differential overlap. CNDO/2 is the main version of CNDO. The method was first introduced by John Pople and collaborators. Background An earlier method was Extended Hückel method, which explicitly ignores electron-electron repulsion terms. It was a method for calculating the electronic energy and the molecular orbitals. CNDO/1 and CNDO/2 were developed from this method by explicitly including the electron-electron repulsion terms, but neglecting many of them, approximating some of them and fitting others to experimental data from spectroscopy. Methodology Quantum mechanics provides equations based on the Hartree–Fock method and the Roothaan equations that CNDO uses to model atoms and their locations. These equations are solve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Chemistry Software
A computation is any type of arithmetic or non-arithmetic calculation that is well-defined. Common examples of computation are mathematical equation solving and the execution of computer algorithms. Mechanical or electronic devices (or, historically, people) that perform computations are known as ''computers''. Computer science is an academic field that involves the study of computation. Introduction The notion that mathematical statements should be 'well-defined' had been argued by mathematicians since at least the 1600s, but agreement on a suitable definition proved elusive. A candidate definition was proposed independently by several mathematicians in the 1930s. The best-known variant was formalised by the mathematician Alan Turing, who defined a well-defined statement or calculation as any statement that could be expressed in terms of the initialisation parameters of a Turing machine. Other (mathematically equivalent) definitions include Alonzo Church's '' lambda-definabil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organizations Disestablished In 2007
An organization or organisation (Commonwealth English; see spelling differences) is an entity—such as a company, or corporation or an institution (formal organization), or an association—comprising one or more people and having a particular purpose. Organizations may also operate secretly or illegally in the case of secret societies, criminal organizations, and resistance movements. And in some cases may have obstacles from other organizations (e.g.: MLK's organization). What makes an organization recognized by the government is either filling out incorporation or recognition in the form of either societal pressure (e.g.: Advocacy group), causing concerns (e.g.: Resistance movement) or being considered the spokesperson of a group of people subject to negotiation (e.g.: the Polisario Front being recognized as the sole representative of the Sahrawi people and forming a partially recognized state.) Compare the concept of social groups, which may include non-organiza ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Distribution
Software distribution is the process of delivering software to the end user. Free software distribution tools GNU Autotools are widely used for which consist of source files written in C++ and the C programming language, but are not limited to these. Commercial software distribution tools * LANDesk Management Suite provides software distribution for Windows, OS X, and Linux. * Dell KACE provides remote administration, software distribution, and software installation to any Windows, Mac, or Linux desktop or server. Distribution tools for mobile devices Distribution of software to small mobile devices such as phones, PDAs and other hand-held terminals is a particular challenge due to their inconsistent connection to the Internet. Some tools that cater to this category of devices are: * Sybase iAnywhere Afaria See also *Provisioning (technology) In telecommunications, provisioning involves the process of preparing and equipping a network to allow it to provide new servi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Force Field (chemistry)
In the context of chemistry, molecular physics, physical chemistry, and molecular modelling, a force field is a computational model that is used to describe the forces between atoms (or collections of atoms) within molecules or between molecules as well as in crystals. Force fields are a variety of interatomic potentials. More precisely, the force field refers to the functional form and parameter sets used to calculate the potential energy of a system on the atomistic level. Force fields are usually used in molecular dynamics or Monte Carlo simulations. The parameters for a chosen energy function may be derived from classical laboratory experiment data, calculations in quantum mechanics, or both. Force fields utilize the same concept as force fields in classical physics, with the main difference being that the force field parameters in chemistry describe the energy landscape on the atomistic level. From a force field, the acting forces on every particle are derived as a g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molden
Molden is a general molecular and electronic structure processing program. Major features * Reads output from the ab initio packages GAMESS (US), Gaussian, MOLPRO, PySCF and from semi-empirical packages such as MOPAC, and supports a number of other formats. * Displays molecular orbitals or electron density Electron density or electronic density is the measure of the probability of an electron being present at an infinitesimal element of space surrounding any given point. It is a scalar quantity depending upon three spatial variables and is typical ... as contour plots or 3D grid plots and output to a number of graphical formats. * Animates reaction paths and molecular vibrations. * A Z-matrix editor. Molden program has been tested on different platforms, namely Linux, Windows NT, Windows95, Windows2000, WindowsXP, MacOSX, Silicon Graphics IRIX, Sun SunOS and Solaris. Ambfor, the main force field module of Molden, is an external program that can be initialized from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CRYSTAL (software)
CRYSTAL is a quantum chemistry ''ab initio'' program, designed primarily for calculations on crystals (3 dimensions), slabs (2 dimensions) and polymers (1 dimension) using translational symmetry, but it can also be used for single molecules.''Computational Chemistry'', David Young, Wiley-Interscience, 2001. Appendix A. A.2.2 pg 334, Crystal It is written by V.R. Saunders, R. Dovesi, C. Roetti, R. Orlando, C.M. Zicovich-Wilson, N.M. Harrison, K. Doll, B. Civalleri, I.J. Bush, Ph. D’Arco, and M. Llunell from Theoretical Chemistry Group at the University of Torino and the Computational Materials Science Group at the Daresbury Laboratory near Warrington in Cheshire, England. The current version is CRYSTAL23. Earlier versions were CRYSTAL88, CRYSTAL92, CRYSTAL95, CRYSTAL98, CRYSTAL03, CRYSTAL06, CRYSTAL09, CRYSTAL14, and CRYSTAL17. Program structure The program is built of two modules: ''crystal'' and ''properties''. The ''crystal'' program is dedicated to perform the SCF calculatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AMPAC
AMPAC is a general-purpose semiempirical quantum chemistry program. It is marketed by Semichem, Inc. and was developed originally by Michael Dewar and his group. The first version of AMPAC (2.1) was made available in 1985 through the Quantum Chemistry Program Exchange (QCPE). Subsequent versions were released through the same source, representing minor updates and optimized versions for other platforms. In 1992, Semichem, Inc. was formed at Professor Dewar's urging to maintain and market the program. ''AMPAC 4.0 with Graphical User Interface'' was released in August of that year. Semichem's current version of AMPAC is 10.http://www.semichem.com/ AMPAC current implements the SAM1, AM1, MNDO, MNDO/d, PM3, MNDOC MINDO/3, RM1 and PM6 semi-empirical methods and AMSOL and COSMO salvation models. See also * Quantum chemistry computer programs Quantum chemistry computer programs are used in computational chemistry to implement the methods of quantum chemistry. Most include the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gaussian Orbital
In computational chemistry and molecular physics, Gaussian orbitals (also known as Gaussian type orbitals, GTOs or Gaussians) are functions used as atomic orbitals in the LCAO method for the representation of electron orbitals in molecules and numerous properties that depend on these. Rationale The use of Gaussian orbitals in electronic structure theory (instead of the more physical Slater-type orbitals) was first proposed by Boys in 1950. The principal reason for the use of Gaussian basis functions in molecular quantum chemical calculations is the 'Gaussian Product Theorem', which guarantees that the product of two GTOs centered on two different atoms is a finite sum of Gaussians centered on a point along the axis connecting them. In this manner, four-center integrals can be reduced to finite sums of two-center integrals, and in a next step to finite sums of one-center integrals. The speedup by 4-5 orders of magnitude compared to Slater orbitals outweighs the extra cost ent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Chemistry
Computational chemistry is a branch of chemistry that uses computer simulations to assist in solving chemical problems. It uses methods of theoretical chemistry incorporated into computer programs to calculate the structures and properties of molecules, groups of molecules, and solids. The importance of this subject stems from the fact that, with the exception of some relatively recent findings related to the hydrogen molecular ion (dihydrogen cation), achieving an accurate quantum mechanical depiction of chemical systems analytically, or in a closed form, is not feasible. The complexity inherent in the many-body problem exacerbates the challenge of providing detailed descriptions of quantum mechanical systems. While computational results normally complement information obtained by chemical experiments, it can occasionally predict unobserved chemical phenomena. Overview Computational chemistry differs from theoretical chemistry, which involves a mathematical description of chem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
