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Reaction Field Method
The reaction field method is used in molecular simulations to simulate the effect of long range dipole-dipole interactions for simulations with periodic boundary conditions. Around each molecule there is a 'cavity' or sphere within which the Coulomb interactions are treated explicitly. Outside of this cavity the medium is assumed to have a uniform dielectric constant. The molecule induces polarization in this media which in turn creates a reaction field, sometimes called the Onsager reaction field. Although Onsager's name is often attached to the technique, because he considered such a geometry in his theory of the dielectric constant, the method was first introduced by Barker and Watts in 1973. The effective pairwise potential becomes: : U_ = q_A q_B \left frac + \frac \right/math> where r_c is the cut-off radius. The reaction field in the center of the cavity is given by : : E_ = \frac \frac where \vec = \sum \mu_i is the total dipole moment of all the molecules in the cavity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periodic Boundary Conditions
Periodic boundary conditions (PBCs) are a set of boundary conditions which are often chosen for approximating a large (infinite) system by using a small part called a ''unit cell''. PBCs are often used in computer simulations and mathematical models. The topology of two-dimensional PBC is equal to that of a ''world map'' of some video games; the geometry of the unit cell satisfies perfect two-dimensional tiling, and when an object passes through one side of the unit cell, it re-appears on the opposite side with the same velocity. In topological terms, the space made by two-dimensional PBCs can be thought of as being mapped onto a torus (compactification). The large systems approximated by PBCs consist of an infinite number of unit cells. In computer simulations, one of these is the original simulation box, and others are copies called ''images''. During the simulation, only the properties of the original simulation box need to be recorded and propagated. The ''minimum-image conventi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lars Onsager
Lars Onsager (November 27, 1903 – October 5, 1976) was a Norwegian-born American physical chemist and theoretical physicist. He held the Gibbs Professorship of Theoretical Chemistry at Yale University. He was awarded the Nobel Prize in Chemistry in 1968. Education and early life Lars Onsager was born in Kristiania (now Oslo), Norway. His father was a lawyer. After completing secondary school in Oslo, he attended the Norwegian Institute of Technology (NTH) in Trondheim, graduating as a chemical engineer in 1925. Career and research In 1925 he arrived at a correction to the Debye-Hückel theory of electrolytic solutions, to specify Brownian movement of ions in solution, and during 1926 published it. He traveled to Zürich, where Peter Debye was teaching, and confronted Debye, telling him his theory was wrong. He impressed Debye so much that he was invited to become Debye's assistant at the Eidgenössische Technische Hochschule (ETH), where he remained until 1928. Johns ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herman Berendsen
Herman Johan Christiaan Berendsen (22 September 1934 – 7 October 2019) was a Dutch chemist. He was a professor of physical chemistry at the University of Groningen from 1967 to 1999. Career Berendsen was born on 22 September 1934 in Apeldoorn. In 1962 he obtained his PhD ''cum laude'' from the University of Groningen, with a dissertation titled: "An NMR study of collagen hydration". In March 1963 Berendsen was appointed lector of physical chemistry at his ''alma mater'', and four years later became full professor. He retired in 1999. At Groningen Berendsen was group leader of molecular dynamics. In 1976 Berendsen and Wilfred van Gunsteren together with the 2013 Nobel Prize in Chemistry winners Martin Karplus and Michael Levitt were involved in the start of theories on molecular calculating. Berendsen was elected a member of the Royal Netherlands Academy of Arts and Sciences in 1979. In 2013 he was awarded the Berni J. Alder Prize by the Centre européen de calcul atomique ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ewald Summation
Ewald summation, named after Paul Peter Ewald, is a method for computing long-range interactions (e.g. electrostatic interactions) in periodic systems. It was first developed as the method for calculating electrostatic energies of ionic crystals, and is now commonly used for calculating long-range interactions in computational chemistry. Ewald summation is a special case of the Poisson summation formula, replacing the summation of interaction energies in real space with an equivalent summation in Fourier space. In this method, the long-range interaction is divided into two parts: a short-range contribution, and a long-range contribution which does not have a singularity. The short-range contribution is calculated in real space, whereas the long-range contribution is calculated using a Fourier transform. The advantage of this method is the rapid convergence of the energy compared with that of a direct summation. This means that the method has high accuracy and reasonable speed when co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monte Carlo
Monte Carlo (; ; french: Monte-Carlo , or colloquially ''Monte-Carl'' ; lij, Munte Carlu ; ) is officially an administrative area of the Principality of Monaco, specifically the ward of Monte Carlo/Spélugues, where the Monte Carlo Casino is located. Informally, the name also refers to a larger district, the Monte Carlo Quarter (corresponding to the former municipality of Monte Carlo), which besides Monte Carlo/Spélugues also includes the wards of La Rousse/Saint Roman, Larvotto/Bas Moulins and Saint Michel. The permanent population of the ward of Monte Carlo is about 3,500, while that of the quarter is about 15,000. Monaco has four traditional quarters. From west to east they are: Fontvieille (the newest), Monaco-Ville (the oldest), La Condamine, and Monte Carlo. Monte Carlo is situated on a prominent escarpment at the base of the Maritime Alps along the French Riviera. Near the quarter's western end is the "world-famous Place du Casino, the gambling center ... that has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Spherocylinder
Hard may refer to: * Hardness, resistance of physical materials to deformation or fracture * Hard water, water with high mineral content Arts and entertainment * ''Hard'' (TV series), a French TV series * Hard (band), a Hungarian hard rock supergroup * Hard (music festival), in the U.S. * ''Hard'' (EP), Goodbye Mr Mackenzie, 1993 * ''Hard'' (Brainpower album), 2008 * ''Hard'' (Gang of Four album), 1983 * ''Hard'' (Jagged Edge album), 2003 * "Hard" (song), a 2009 song by Rihanna * "Hard", a song by Royce da 5'9" from the 2016 album ''Layers'' * "Hard", a song by Why Don't We from the 2018 album ''8 Letters'' * ''Hard'', a 2017 EP from the band The Neighbourhood *"Hard", a song by Sophie from the 2015 compilation album ''Product'' Places * Hard, Austria * Hard (Zürich), Switzerland Other uses * Hard (surname) * Nickname of Masaki Sumitani ( HardGay / HardoGay ) * Hard (nautical), a beach or slope convenient for hauling out vessels * Hard (video game player), Anthony Barkho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stockmayer System
The Stockmayer potential is a mathematical model for representing the interactions between pairs of atoms or molecules. It is defined as a Lennard-Jones potential with a point electric dipole moment The electric dipole moment is a measure of the separation of positive and negative electrical charges within a system, that is, a measure of the system's overall polarity. The SI unit for electric dipole moment is the coulomb-meter (C⋅m). The .... A Stockmayer liquid consists of a collection of spheres with point dipoles embedded at the centre of each. These spheres interact both by Lennard-Jones and dipolar interactions. In the absence of the point dipoles, the spheres face no rotational friction and the translational dynamics of such LJ spheres have been studied in detail. This system, therefore, provides a simple model where the only source of rotational friction is dipolar interactions References M. E. Van Leeuwe "Deviation from corresponding-states behaviour for polar fluids" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
