Difference between revisions of "United-atom model"

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==Parameters==
 
==Parameters==
 
==References==
 
==References==
 +
#[http://dx.doi.org/10.1080/00268978800101181 Rolf Lustig and William A. Steele "On the thermodynamics of liquid propane", Molecular Physics '''65''' pp. 475-486 (1988)]
 +
#[http://dx.doi.org/10.1063/1.454894 Sumnesh Gupta,    Jia-an Yang and Neil R. Kestner "Computer modeling of liquid propane using three-site potential models", Journal of Chemical Physics '''89''' pp. 3733-3741 (1988)]
 +
#[http://dx.doi.org/10.1063/1.456853 Søren Toxvaerd "Molecular dynamics calculation of the equation of state of liquid propane", Journal of Chemical Physics '''91''' pp. 3716-3720 (1989)]
 
#[http://dx.doi.org/10.1063/1.458709  Søren Toxvaerd "Molecular dynamics calculation of the equation of state of alkanes", Journal of Chemical Physics '''93''' pp. 4290-4295 (1990)]
 
#[http://dx.doi.org/10.1063/1.458709  Søren Toxvaerd "Molecular dynamics calculation of the equation of state of alkanes", Journal of Chemical Physics '''93''' pp. 4290-4295 (1990)]
 
[[Category: Models]]
 
[[Category: Models]]

Revision as of 20:54, 16 October 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

  1. Rolf Lustig and William A. Steele "On the thermodynamics of liquid propane", Molecular Physics 65 pp. 475-486 (1988)
  2. Sumnesh Gupta, Jia-an Yang and Neil R. Kestner "Computer modeling of liquid propane using three-site potential models", Journal of Chemical Physics 89 pp. 3733-3741 (1988)
  3. Søren Toxvaerd "Molecular dynamics calculation of the equation of state of liquid propane", Journal of Chemical Physics 91 pp. 3716-3720 (1989)
  4. Søren Toxvaerd "Molecular dynamics calculation of the equation of state of alkanes", Journal of Chemical Physics 93 pp. 4290-4295 (1990)