Difference between revisions of "United-atom model"

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In the '''united-atom model''' the <math>CH_2</math> and <math>CH_3</math> units
 
In the '''united-atom model''' the <math>CH_2</math> and <math>CH_3</math> units
are treated as one point, i.e. the hydrogen atoms are incorporated within  
+
are treated as one unified interaction site (hence ''united-atom''), i.e. the hydrogen atoms are incorporated within  
 
the carbon atoms and are not expressed explicitly. Many [[force fields]]
 
the carbon atoms and are not expressed explicitly. Many [[force fields]]
 
make use of this approximation in order to reduce the computational  
 
make use of this approximation in order to reduce the computational  

Revision as of 19:22, 21 August 2007

In the united-atom model the CH_2 and CH_3 units are treated as one unified interaction site (hence united-atom), i.e. the hydrogen atoms are incorporated within the carbon atoms and are not expressed explicitly. Many force fields make use of this approximation in order to reduce the computational overheads. For example, n-hexane consists of 6 carbon atoms and 14 hydrogen atoms. A fully-atomistic model of n-hexane would require 20 interaction sites. Using the united-atom approximation, this reduces to two CH_3 sites and four CH_2 sites, a significant reduction.

Justification

Parameters

References