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atoms). This freedom exists down to absolute zero, which was previously seen as an absolute one-of-a-kind configuration. The existence of these multiple configurations (choices for each H of orientation along O--O axis) that meet the rules of absolute zero (2-in 2-out for each O) amounts to randomness, or in other words, entropy. Thus systems that can take multiple configurations at or near absolute zero are said to have residual entropy.
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317:. In water, each oxygen atom is bonded to two hydrogen atoms. However, when water freezes it forms a tetragonal structure where each oxygen atom has four hydrogen neighbors (due to neighboring water molecules). The hydrogen atoms sitting between the oxygen atoms have some degree of freedom as long as each oxygen atom has two hydrogen atoms that are 'nearby', thus forming the traditional H
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therefore the same residual entropy. One of the interesting properties of geometrically frustrated magnetic materials such as spin ice is that the level of residual entropy can be controlled by the application of an external magnetic field. This property can be used to create one-shot refrigeration systems.
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O water molecule. However, it turns out that for a large number of water molecules in this configuration, the hydrogen atoms have a large number of possible configurations that meet the 2-in 2-out rule (each oxygen atom must have two 'near' (or 'in') hydrogen atoms, and two far (or 'out') hydrogen
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magnetic spins and lie on the corners of network of corner-sharing tetrahedra. This material is thus analogous to water ice, with the exception that the spins on the corners of the tetrahedra can point into or out of the tetrahedra, thereby producing the same 2-in, 2-out rule as in water ice, and
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Although water ice was the first material for which residual entropy was proposed, it is generally very difficult to prepare pure defect-free crystals of water ice for studying. A great deal of research has thus been undertaken into finding other systems that exhibit residual entropy.
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168:(with all of the carbon monoxide molecules oriented in the same direction). Because of this, the crystal is locked into a state with
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systems in particular often exhibit residual entropy. An important example is
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The residual entropy has a somewhat special significance compared to other
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One of the first examples of residual entropy was pointed out by
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residual entropy, which can be computed directly from any
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380:"Fluid Viscosity-Residual Entropy Correlation"
425:. San Francisco: W.H.Freeman and Co. p.
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270:Another example is any amorphous solid (
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260:{\displaystyle S=Nk\ln(2)=nR\ln(2)}
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378:Novak, Lawrence T. (2011-11-16).
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359:Geometrical frustration
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188:{\displaystyle 2^{N}}
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354:Ice rules
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