United-atom model: Difference between revisions
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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 | 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 18:22, 21 August 2007
In the united-atom model the and 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 Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle CH_3} sites and four Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle CH_2} sites, a significant reduction.
