# Computer simulation techniques

"In those pieces of apparatus [computing machines] I see not only devices to make the forces of nature serviceable in new ways, no, I view them with much greater respect; I dare say that I see in them the true devices for unveiling the essence of things"

- Ludwig Eduard Boltzmann
^{[1]}

**Computer simulations** are used to obtain quantitative results, under various thermodynamic conditions, for realistic models which are parametrised to study a specific atomic or molecular system with a certain degree of realism, or force fields, which consist of transferable parameters for molecular sub-units, usually at the atomistic level. Force fields are designed to be applicable to a variety of molecular systems, in particular for flexible molecules. Computer simulations are also used to perform "computer experiments" on idealised models in order to test theories with a view to arriving at a better understanding of the underlying physics of a system.

The two predominant computer simulation techniques used in the study of soft condensed matter are:

and

For a list of some of the computer programs available see:

## Material common to both techniques[edit]

- Coarse graining
- Computation of phase equilibria
- Configuration analysis
- Constrained cell method
- Dissipative particle dynamics
- Electrostatics
- Ergodic hypothesis
- Expanded ensemble method
- Finite size scaling
- Force fields
- Gibbs-Duhem integration
- Hybrid Monte Carlo
- Iterative Boltzmann inversion
- Models
- Multicanonical ensemble
- Neighbour lists
- Path integrals
- Periodic boundary conditions
- Self-referential method
- Smooth Particle methods
- Statistical-temperature simulation algorithm
- Synthetic method
- Tempering methods
- Test area method
- Test volume method
- Thermostats
- Wandering interface method
- Widom test-particle method

## Interesting reading[edit]

- W. W. Wood "Early history of computer simulations in statistical mechanics" in "Molecular-dynamics simulation of statistical-mechanical systems" (Eds. Giovanni Ciccotti and William G. Hoover) pp. 3-14 Società Italiana di Fisica (1986)
- Daan Frenkel and Jean-Pierre Hansen "Understanding liquids: a computer game?", Physics World
**9**pp. 35–42 (April 1996) - Wm. G. Hoover "50 Years of Computer Simulation -- A Personal View", arXiv:0812.2086v2 (2008)
- Wilfred F. van Gunsteren, and Alan E. Mark "Validation of molecular dynamics simulation", Journal of Chemical Physics
**108**pp. 6109-6116 (1998) - Richard P. Feynman "Simulating Physics With Computers", International Journal of Theoretical Physics
**21**pp. 467-488 (1982) - Michael P. Allen and David Quigley "Some comments on Monte Carlo and molecular dynamics methods", Molecular Physics
**111**pp. 3442-3447 (2013)

- ↑ "The Second Law of the Mechanical Theory of Heat" (1886) (Note: this quote and reference is taken from p. 110 of Engelbert Broda (English translation with Larry Gay) "Ludwig Boltzmann - Man, Physicist, Philosopher" Ox Bow Press (1983) ISBN 0918024242 , but I have as yet been unable to corroborate this reference).