Tuesday, January 7, 2014

One might have thought that I would write something about the Higgs particle is today because I am


One might have thought that I would write something about the Higgs particle is today because I am a physicist, but I did not do. The reason is that elementary particle physics tanita weegschaal and high energy physics is quite far away from what I myself do, and there are others who can write better about Higgs (Research and Progress, for example). Instead, it's this year's chemistry price that is at least in the vicinity of some things I do. Furthermore, as it suffers from a rather sharp over simplification in the press release so thought I would write a small text about it here. The Nobel Prize in Chemistry this year awarded to Martin Karplus, Michael Levitt tanita weegschaal and Arieh Warshel "for the development of multi-scale modeling of complex chemical systems." They have managed to combine three different types of computer models to get a good description of such reactions between biomolecules (proteins, etc.) without necessarily having excessively long computation times. This has been achieved by dividing the system being studied in various parts, which are described using different methods. We can start at the back, with the atoms directly involved in the chemical reaction. To get a good picture of what happens here will need to acquire a model of how the atoms' electrons behave. It is the distribution of electrons around nuclei that determines tanita weegschaal if the atoms are squeezed together or not, and how strong the bond is (which I wrote about here). To keep track of the electrons you use what is called the first PRINCIPLE calculations, where one solves Shrödingers equation. With such methods it is assumed that all nuclei sitting in a certain way, and then determines how the electrons tanita weegschaal are distributed around them. Based on the electron distribution, tanita weegschaal one can calculate the forces acting on the nuclei tanita weegschaal and how they will move away because of the forces. (Or how they should tanita weegschaal move away to get the lowest possible energy. It depends on what you want.) The next area comprises all the atoms that are part of the molecules, but which are not directly involved in the reaction. Because biomolecules are often quite large so there may be many such atoms, so many that if one were to describe all first-principle methods would hardly be able to perform the calculation. Rather than describe them using the so-called model potentials. A potential tanita weegschaal model is designed to describe the forces between the atoms in a material will look, for example, a model potential include terms corresponding to the force between two charged particles (ionic) or angle-dependent terms that correspond covalent bonds. Frequently, participants using the results from the first principle calculations and experiments to determine exactly how the potential to look like. Because you do not have to keep track of the electrons, but only consider the atoms as balls with a certain mass require these kinds of calculations much less computing power than the first principle calculations. It is also the link between the first principle methods tanita weegschaal and model potentials as the press release in my opinion is overly simplistic. It says that the laureates' managed to get Newton's classical laws of physics to work with the fundamentally different quantum physics, "but it's not quite that simple. Both first-principle calculations and model potential calculations using namely classical Newtonian laws to calculate the atomic nuclei, which account for the bulk of the mass moves. The difference between the methods lies in how to calculate the force between tanita weegschaal the nuclei, and which is the first principle methods based directly on quantum physics while model potentials, it is indirect, in that they are designed to mimic the results of first principle calculations (or experiments). So it's not really about to reconcile quantum physics and classical physics, but about two ways to describe the forces in a system - which of course does not make Laureates bet less awesome. Finally, we must also describe what's tanita weegschaal around the molecules being studied. Because it is biomolecules want you probably often study them in some form of water solution, but you are not especially tanita weegschaal interested in how each water molecule behaves. Therefore, ignoring the molecules and describes the surroundings as a smooth, homogeneous tanita weegschaal mass. There is an even less demanding in terms of computing power than molecular dynamics, but can of course not to use if you want to know how atoms are moving. Another interesting thing is that the principle behind the Nobel Laureates' contribution, tanita weegschaal that the use of different calculation methods for different parts of a system, now also used to count on eg how cracks form in the material. In fact it was the first thing I thought of when I heard about what they got for the price.
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