# Difference between revisions of "United-atom model"

Carl McBride (talk | contribs) |
Carl McBride (talk | contribs) |
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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 | ||

− | overheads. | + | 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 <math>CH_3</math> sites and four <math>CH_2</math> sites, a significant reduction. | ||

+ | ==Justification== | ||

+ | ==Parameters== | ||

==References== | ==References== | ||

[[Category: Models]] | [[Category: Models]] |

## Revision as of 10:44, 30 May 2007

In the **united-atom model** the and units
are treated as one point, 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 sites and four sites, a significant reduction.