Structure optimization

Element: structureoptimization

The element structureoptimization activates the optimization of atomic postions.

Type:	no content
XPath:	/input/structureoptimization

This element allows for specification of the following attributes: epsforce, resume, tau0atm

Attribute: epsforce

Convergence tolerance for the forces during a structural optimization run.

Type:	no content
Default:	"5.0d-5"
Use:	optional
XPath:	/input/structureoptimization

Attribute: resume

Resumption of a structural optimization run using the density in STATE.OUT, but with positions from input.xml.

Type:	boolean
Default:	"false"
Use:	optional
XPath:	/input/structureoptimization/@resume

Attribute: tau0atm

Parameter determining the step size for structural optimization.

In each step $m$ of a structural optimization run, atom $\alpha$ is displaced according to

(1)

\begin{align} {\bf r}_{\alpha}^{m+1}={\bf r}_{\alpha}^m+\tau_{\alpha}^m \left({ \bf F}_{\alpha}^m+{ \bf F}_{\alpha}^{m-1}\right), \end{align}

i.e., the magnitude of the displacement in step $m$ is proportional to $\tau_{\alpha}^m$. For the initial step, $\tau_{\alpha}^0$ is set to tau0atm. If the forces of two subsequent steps have the same sign, $\tau_{\alpha}^m$ is increased by $\tau_{\alpha}^0$. Otherwise, $\tau_{\alpha}^m$ is reset to $\tau_{\alpha}^0$.

Type:	fortrandouble
Default:	"0.2d0"
Use:	optional
XPath:	/input/structureoptimization/@tau0atm

Reused Elements

The following elements can occur more than once in the input file. There for they are listed separately.

Data Types

The Input definition uses derived data types. These are described here.