PREC: Difference between revisions

Revision as of 13:37, 12 February 2011

Default: PREC	= Medium	for VASP.4.X
	= Normal	for VASP.5.X

Description: PREC specifies the "precision"-mode.

Changing the PREC parameter influences the defaults for four sets of parameters (ENCUT; NGX, NGY, NGZ; NGXF, NGYF, NGZF, and ROPT):

PREC	NGX,Y,Z	NGXF,YF,ZF	ROPT
Normal	3/2×G_cut	2×NGX	-5×10^-4
Single	3/2×G_cut	NGX	-5×10^-4
Accurate	2×G_cut	2×NGX	-2.5×10^-4
Low	3/2×G_cut	3×G_aug	-1×10^-2
Medium	3/2×G_cut	4×G_aug	-2×10^-3
High	2×G_cut	16/3×G_aug	-4×10^-4

where

[math]\displaystyle{ E_{\rm cut}=\frac{\hbar^2}{2m_e}G_{\rm cut}^2 \qquad E_{\rm aug}=\frac{\hbar^2}{2m_e}G_{\rm aug}^2 }[/math]

with E_cut=ENCUT and E_aug=ENAUG.

Mind: the settings PREC=Normal and PREC=Accurate are only available in VASP.4.5 and newer versions. The setting PREC=Single is only available as of VASP.5.1.

or an equation array or another example in another section

and an array of equations

An eqnarray

[math]\displaystyle{ \begin{align} \frac{e}{\pi} & =\int_\Omega \psi (\mathbf{r}) d\mathbf{r} \\ a & = b \\ \end{align} }[/math]

Related Tags and Sections

NGX, NGY, NGZ, NGXF, NGYF, NGZF, ENCUT, ENAUG, ENMAX

Contents

@@ Line 1: / Line 1: @@
-{{TAGDEF|PREC|0}}
+{{TAGDEF|PREC|Low {{!}} Medium {{!}} High {{!}} Normal {{!}} Single {{!}} Accurate}}
-{{DEF|PREC|2|hallo|1|byebye|2|if [[ICHARG]]{{=}}11}}
+{{DEF|PREC|Medium|for VASP.4.X|Normal|for VASP.5.X}}
-The precision tag
+Description: {{TAG|PREC}} specifies the "precision"-mode.
+----
+Changing the {{TAG|PREC}} parameter influences the defaults for four sets of parameters ({{TAG|ENCUT}}; {{TAG|NGX}}, {{TAG|NGY}}, {{TAG|NGZ}}; {{TAG|NGXF}}, {{TAG|NGYF}}, {{TAG|NGZF}}, and {{TAG|ROPT}}):
-== Intro ==
+::{| cellpadding="5" cellspacing="0" border="1"
+|{{TAG|PREC}} || {{TAG|NGX}},Y,Z || {{TAG|NGXF}},YF,ZF || {{TAG|ROPT}}
+|-
+| Normal || 3/2&times;G<sub>cut</sub> || 2&times;{{TAG|NGX}} || -5&times;10<sup>-4</sup>
+|-
+| Single || 3/2&times;G<sub>cut</sub> || {{TAG|NGX}} || -5&times;10<sup>-4</sup>
+|-
+| Accurate || 2&times;G<sub>cut</sub> || 2&times;{{TAG|NGX}}|| -2.5&times;10<sup>-4</sup>
+|-
+| Low || 3/2&times;G<sub>cut</sub> || 3&times;G<sub>aug</sub> || -1&times;10<sup>-2</sup>
+|-
+| Medium || 3/2&times;G<sub>cut</sub> || 4&times;G<sub>aug</sub> || -2&times;10<sup>-3</sup>
+|-
+| High ||  2&times;G<sub>cut</sub> || 16/3&times;G<sub>aug</sub> || -4&times;10<sup>-4</sup>
+|}
+where
+:<math>E_{\rm cut}=\frac{\hbar^2}{2m_e}G_{\rm cut}^2 \qquad E_{\rm aug}=\frac{\hbar^2}{2m_e}G_{\rm aug}^2</math>
+with E<sub>cut</sub>={{TAG|ENCUT}} and E<sub>aug</sub>={{TAG|ENAUG}}.
+'''Mind''': the settings {{TAG|PREC}}=Normal and {{TAG|PREC}}=Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG|PREC}}=Single is only available as of VASP.5.1.
-An equation
-<math>
-\frac{e}{\pi}=2y
-</math>
 or [[PREC#eqnarray|an equation array]] or [[LREAL#cproj|another example]] in another section
-and set some tags into your {{FILE|INCAR}} file
- PREC = A
- GGA  = PE
-== And another section ==
 and an array of equations
@@ Line 33: / Line 42: @@
 </math>
+== Related Tags and Sections ==
-== And one more ==
+{{TAG|NGX}},
+{{TAG|NGY}},
+{{TAG|NGZ}},
-== And again ==
+{{TAG|NGXF}},
+{{TAG|NGYF}},
+{{TAG|NGZF}},
+{{TAG|ENCUT}},
+{{TAG|ENAUG}},
+{{TAG|ENMAX}}
 ----