# Materials

The Materials element stores information about any materials used in the simulation. To use one of VSim’s pre-defined materials, highlight the Materials element and then switch from 3D View to Database in the Geometry View (see VSim User Guide: Setup Window for Visual-setup Simulations for a picture of the Geometry View). To add one of the pre-defined materials from the table, highlight the material then press Add To Simulation button in upper right hand corner of the VSim Composer window. The material will now be listed under the Materials element. To access a wider selection of materials you may load the emthermal.vmat file by right-clicking on the Materials element and selecting Import Materials. You may also import your own customized material (see Customizing Materials below).

The editable properties of the materials are:

kind (not editable)
The kind of material (eg dielectric, conductor, particle absorber, permeable, etc), as defined in the .vmat file.
heat capacity
The heat capacity of the material.
thermal conductivity
The thermal conductivity of the material.
resistance
The resistance of the material.
conductivity
The conductivity of the material.
relative permittivity
The relative permittivity of the material.

## Customizing Materials

Custom materials properties can be created in a text editor and imported into VSim. To import a custom material:

1. Go to the “data” folder at the top level of the VSim installation directory. On Windows this will be in “Program Files\Tech-X (Win64)\VSim-9.0\data". On Mac and Linux, there is no standard location.

2. Create a new text file that ends in the .vmat extension. For example: emthermalcustom.vmat.

3. Open the default materials file emthermal.vmat.

4. Copy a block from emthermal.vmat to emthermalcustom.vmat to use as a sample.

5. Edit the title and properties of the block as needed. For example:

<Material FreshWater>
<strings>
kind = "dielectric"
</strings>
<params>
heat capacity = 4.184
conductivity = 0.005
relative permittivity = 80.4
thermal conductivity = 0.6065
</params>
</Material>


6. Save the new file.

7. Back in VSim, click on the Materials element in your simulation and then click Add –> Import Materials. A file browser will appear with the data directory already open.

8. Select your custom vmat file. If you do not see your vmat file in the directory, navigate to where you saved it.

9. The view will change to the Database tab and the materials added will be available here.