###### COMPUTER SIMULATIONS OF POLAR LIQUIDS IN AN EXTERNAL ELECTRIC FIELD

**Dr. Ahmad Khalaf**

Department of Electrical, faculty of Engineering, lraqi University, Iraq.

**Introduction**

The computer is known as an electronic calculating machine, which has been developed to solve the difficult calculations involved in the development of nuclear weapons and in cryptography. Before the computer simulation was introduced as one important research method in materials science, the precise material structures, properties and their relationships are investigated only through time-consuming and expensive experiments. On the other hand, one can only go through employing a theory that provides an approximate description of the available material that predict the properties of a molecular substance. Because of the complexity of some systems, such approximations are unavoidable. With sufficient information about the intermolecular interactions, theories can estimate the observed or deliver desired properties. Unfortunately, our knowledge of the intermolecular Interactions fairly limited. Essentially, computer simulations allow us to obtain exact results for a given model system. We can then compare the results with those from the experiment and/or compare the analytical results of the theory[1].

In nature, polarizability is a fundamental property of all atoms and molecules. The point polarizability can affect macroscopic properties of the material, e.g. the dielectric constant and critical parameters, by the induced dipole moment. The additional polarizability on the point dipole makes the model even more complicated, but also more realistic. Although some simulation works have been previously performed, polarizable models for polar liquids are still challenging. This is due to the difficulty mentioned the simulation[2, 3].

For many years, chemists and physicists have studied the phase behavior of dipolar liquids[4-6], since dipolar liquids are very good model systems for ferrofluid. Ferrofluid are liquids that react to external fields. Because of the controllability of their viscosity, thermal conductivity by means of external fields, such liquids have very extensive technical applications. In the aerospace sector, attempts have also been made to apply some special properties of these materials. In medicine, for example, Ferrofluides are used for cancer detection by the so-called magnetic resonance spectroscopy, or by modifying the upper part which attached the active ingredients for cancer treatment.