1.. index:: timestep
2
3timestep command
4================
5
6Syntax
7""""""
8
9.. parsed-literal::
10
11   timestep dt
12
13* dt = timestep size (time units)
14
15Examples
16""""""""
17
18.. code-block:: LAMMPS
19
20   timestep 2.0
21   timestep 0.003
22
23Description
24"""""""""""
25
26Set the timestep size for subsequent molecular dynamics simulations.
27See the :doc:`units <units>` command for the time units associated with
28each choice of units that LAMMPS supports.
29
30The default value for the timestep size also depends on the choice of
31units for the simulation; see the default values below.
32
33When the :doc:`run style <run_style>` is *respa*, dt is the timestep for
34the outer loop (largest) timestep.
35
36Restrictions
37""""""""""""
38 none
39
40Related commands
41""""""""""""""""
42
43:doc:`fix dt/reset <fix_dt_reset>`, :doc:`run <run>`,
44:doc:`run_style <run_style>` respa, :doc:`units <units>`
45
46Default
47"""""""
48
49+--------------------------------+---------------+-----------------------+
50| choice of :doc:`units <units>` | time units    | default timestep size |
51+--------------------------------+---------------+-----------------------+
52| lj                             | :math:`\tau`  | 0.005 :math:`\tau`    |
53+--------------------------------+---------------+-----------------------+
54| real                           | fs            | 1.0 fs                |
55+--------------------------------+---------------+-----------------------+
56| metal                          | ps            | 0.001 ps              |
57+--------------------------------+---------------+-----------------------+
58| si                             | s             | 1.0e-8 s (10 ns)      |
59+--------------------------------+---------------+-----------------------+
60| cgs                            | s             | 1.0e-8 s (10 ns)      |
61+--------------------------------+---------------+-----------------------+
62| electron                       | fs            | 0.001 fs              |
63+--------------------------------+---------------+-----------------------+
64| micro                          | :math:`\mu`\ s| 2.0 :math:`\mu`\ s    |
65+--------------------------------+---------------+-----------------------+
66| nano                           | ns            | 0.00045 ns            |
67+--------------------------------+---------------+-----------------------+
68