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Free Energy Perturbation
Free energy perturbation (FEP) is a method based on statistical mechanics that is used in computational chemistry for computing free energy differences from molecular dynamics or Metropolis Monte Carlo simulations. The FEP method was introduced by Robert W. Zwanzig in 1954. According to the free-energy perturbation method, the free energy difference for going from state A to state B is obtained from the following equation, known as the ''Zwanzig equation'': :\Delta F(\mathbf \rightarrow \mathbf) = F_\mathbf - F_\mathbf = -k_\mathrm T \ln \left \langle \exp \left ( - \frac \right ) \right \rangle _\mathbf where ''T'' is the temperature, ''k''B is Boltzmann's constant, and the angular brackets denote an average over a simulation run for state A. In practice, one runs a normal simulation for state A, but each time a new configuration is accepted, the energy for state B is also computed. The difference between states A and B may be in the atom types involved, in which case the Î ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Mechanics
In physics, statistical mechanics is a mathematical framework that applies statistical methods and probability theory to large assemblies of microscopic entities. It does not assume or postulate any natural laws, but explains the macroscopic behavior of nature from the behavior of such ensembles. Statistical mechanics arose out of the development of classical thermodynamics, a field for which it was successful in explaining macroscopic physical properties—such as temperature, pressure, and heat capacity—in terms of microscopic parameters that fluctuate about average values and are characterized by probability distributions. This established the fields of statistical thermodynamics and statistical physics. The founding of the field of statistical mechanics is generally credited to three physicists: * Ludwig Boltzmann, who developed the fundamental interpretation of entropy in terms of a collection of microstates *James Clerk Maxwell, who developed models of probability di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QM/MM
The hybrid QM/MM (quantum mechanics/molecular mechanics) approach is a molecular simulation method that combines the strengths of ''ab initio'' QM calculations (accuracy) and MM (speed) approaches, thus allowing for the study of chemical processes in solution and in proteins. The QM/MM approach was introduced in the 1976 paper of Warshel and Levitt. They, along with Martin Karplus, won the 2013 Nobel Prize in Chemistry for "the development of multiscale models for complex chemical systems". Efficiency An important advantage of QM/MM methods is their efficiency. The cost of doing classical molecular mechanics (MM) simulations in the most straightforward case scales as ''O''(''N''2), where ''N'' is the number of atoms in the system. This is mainly due to electrostatic interactions term (every particle interacts with everything else). However, use of cutoff radius, periodic pair-list updates and more recently the variations of the particle mesh Ewald (PME) method has reduced t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Q (software)
Q is a computer software package for molecular dynamics (MD) simulation (current release: Q6). Unlike other MD codes, it has specialized since its conception (Marelius et al. 1998) on three specific types of free energy calculations. These calculations are based on the methods: '' empirical valence bond'' (EVB), ''free energy perturbation'' (FEP), and ''linear interaction energy'' (LIE), as well as, more recently, also path integral calculations using the bisection quantum classical path (BQCP) approach. The methods in which the program specializes can return quantitative calculations of the energy balance which occurs in proteins and nucleic acids. It can provide insight into key problems in biochemistry such as, energetic details on parts of the translation mechanism in mitochondrial ribosomes (Lind et al. 2013), or details in enzymatic reactions (Mones et al. 2013), among others. The program is similar to GROMACS in being force-field agnostic, meaning that it provides no f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tinker (software)
Tinker, previously stylized as TINKER, is a suite of computer software applications for molecular dynamics simulation. The codes provide a complete and general set of tools for molecular mechanics and molecular dynamics, with some special features for biomolecules. The core of the software is a modular set of callable routines which allow manipulating coordinates and evaluating potential energy and derivatives via straightforward means. Tinker works on Windows, macOS, Linux and Unix. The source code is available free of charge to non-commercial users under a proprietary license. The code is written in portable FORTRAN 77, Fortran 95 or CUDA with common extensions, and some C. Core developers are: (athe Jay Ponder lab at the Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri. Laboratory head Ponder is Full Professor of Chemistry, and of Biochemistry & Molecular Biophysics; (bthe Pengyu Ren lab at the Department of Biomedical Engineering Universit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NAMD
Nanoscale Molecular Dynamics (NAMD, formerly Not Another Molecular Dynamics Program) is computer software for molecular dynamics simulation, written using the Charm++ parallel programming model. It is noted for its parallel efficiency and is often used to simulate large systems (millions of atoms). It has been developed by the collaboration of the Theoretical and Computational Biophysics Group (TCB) and the Parallel Programming Laboratory (PPL) at the University of Illinois at Urbana–Champaign. It was introduced in 1995 by Nelson ''et al.'' as a parallel molecular dynamics code enabling interactive simulation by linking to the visualization code VMD. NAMD has since matured, adding many features and scaling beyond 500,000 processor cores. NAMD has an interface to quantum chemistry packages ORCA and MOPAC, as well as a scripted interface to many other quantum packages. Together with Visual Molecular Dynamics (VMD) and QwikMD, NAMD's interface provides access to hybrid QM/MM simul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MacroModel
MacroModel is a computer program for molecular modelling of organic compounds and biopolymers. It features various chemistry force fields, plus energy minimizing algorithms, to predict geometry and relative conformational energies of molecules. MacroModel is maintained by Schrödinger, LLC. It performs simulations in the framework of classical mechanics, also termed ''molecular mechanics'', and can perform molecular dynamics simulations to model systems at finite temperatures using stochastic dynamics and mixed Monte Carlo algorithms. ''MacroModel'' supports Windows, Linux, macOS, Silicon Graphics (SGI) IRIX, and IBM AIX AIX (Advanced Interactive eXecutive, pronounced , "ay-eye-ex") is a series of proprietary Unix operating systems developed and sold by IBM for several of its computer platforms. Background Originally released for the IBM RT PC RISC .... The Macromodel software package was first been described in the scientific literature in 1990, and has b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desmond (software)
Desmond is a software package developed at D. E. Shaw Research to perform high-speed molecular dynamics simulations of biological systems on conventional computer clusters. The code uses novel parallel algorithms and numerical methods to achieve high performance on platforms containing multiple processors, but may also be executed on a single computer. The core and source code are available at no cost for non-commercial use by universities and other not-for-profit research institutions, and have been used in the Folding@home distributed computing project. Desmond is available as commercial software through Schrödinger, Inc. Molecular dynamics program Desmond supports algorithms typically used to perform fast and accurate molecular dynamics. Long-range electrostatic energy and forces can be calculated using particle mesh Ewald-based methods. Constraints can be enforced using the M-SHAKE algorithm. These methods can be used together with time-scale splitting (RESPA-based) in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CHARMM
Chemistry at Harvard Macromolecular Mechanics (CHARMM) is the name of a widely used set of force fields for molecular dynamics, and the name for the molecular dynamics simulation and analysis computer software package associated with them. The CHARMM Development Project involves a worldwide network of developers working with Martin Karplus and his group at Harvard to develop and maintain the CHARMM program. Licenses for this software are available, for a fee, to people and groups working in academia. Force fields The CHARMM force fields for proteins include: united-atom (sometimes termed ''extended atom'') CHARMM19, all-atom CHARMM22 and its dihedral potential corrected variant CHARMM22/CMAP, as well as later versions CHARMM27 and CHARMM36 and various modifications such as CHARMM36m and CHARMM36IDPSFF. In the CHARMM22 protein force field, the atomic partial charges were derived from quantum chemical calculations of the interactions between model compounds and water. Furthermore ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BOSS (molecular Mechanics)
Boss may refer to: Occupations * Supervisor, often referred to as boss * Air boss, more formally, air officer, the person in charge of aircraft operations on an aircraft carrier * Crime boss, the head of a criminal organization * Fire boss, a person in charge of mine safety * Pit boss, the person who looks after the employees who work in a casino pit * Political boss, a person who controls a political region or constituency Places United States * Boss, Missouri, an unincorporated community * Boss, Texas, an unincorporated community * Bosstown, Wisconsin, an unincorporated community Moon * Boss (crater), a lunar crater People As a real name *Boss (surname) *Boss Mustapha, politician, Secretary of Nigerian government As a nickname or stage name Athletes * Lance Armstrong ("", born 1971), former professional cyclist * Sasha Banks (born 1992), American professional wrestler * Tomás Boy ("", born 1952), former Mexican professional football player and current coach * Bobby ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AMBER
Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In Maxine N. Lurie and Marc Mappen (eds.) ''Encyclopedia of New Jersey'', Rutgers University Press, . Amber is used in jewelry and has been used as a healing agent in folk medicine. There are five classes of amber, defined on the basis of their chemical constituents. Because it originates as a soft, sticky tree resin, amber sometimes contains animal and plant material as inclusions. Amber occurring in coal seams is also called resinite, and the term ''ambrite'' is applied to that found specifically within New Zealand coal seams. Etymology The English word ''amber'' derives from Arabic (ultimately from Middle Persian ''ambar'') via Middle Latin ''ambar'' and Middle French ''ambre''. The word was adopted in Middle English in the 14th c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
