# The minimize keyword

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## Purpose

- This keyword is used to minimize the energy of the system. Currently, only the
**steepest descent**method has been implemented.

## Grammar

- This keyword is used as follows:

minimize sd force_tolerance maximal_number_of_steps

`sd`

means using the**steepest descent**method.`force_tolerance`

is in units of eV/A. When the largest absolute force component among the [math]3N[/math] force components in the system is smaller than`force_tolerance`

, the energy minimization process will stop even though the number of steps (interations) performed is smaller than`maximal_number_of_steps`

`maximal_number_of_steps`

is the maximal number of steps (interations) to be performed for the energy minimization process.

## Examples

### Example 1

- For example, the command

minimize sd 1.0e-6 10000

means that one wants to do an energy minimization using the **steepest descent** method, with a force tolerance of 1.0e-6 eV/A for maximally 10000 steps.

### Example 2

- If you have no idea how small
`force_tolerance`

should be, you can simply asign a negative number to it:

minimize sd -1 10000

In this case, the energy minimization process will definitely run 10000 steps.

## Caveats

- This keyword should occur after all the
`potential`

keywords.

- Currently, the simulation box is fixed during the energy minimization.