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# LIGGGHTS 2.X vs. LIGGGHTS 1.5.3 - syntax changes

## Introduction:

This is a short outline of the most important changes in LIGGGHTS 2.X compared to LIGGGHTS 1.5.3 regarding the syntax of major commands. The motivation for these changes was to make the script language more readable and to improve extendability (in the sense of object oriented programming) with respect to modelling approaches.

## Commands covered by this tutorial:

- atom_style sphere (formerly atom_style granular)
- dump mesh/stl (formerly dump stl)
- dump mesh/vtk (formerly dump mesh/gran/VTK)
- fix heat/gran
- fix mesh/surface (formerly fix mesh/gran)
- fix mesh/surface/stress (formerly fix mesh/gran/stressanalysis)
- fix move/mesh (formerly fix move/mesh/gran)
- fix wall/gran/*
- pair_style gran/*

  ## Changes in syntax for each command:

  Changes are indicated as follows

      OLD: old_syntax
      NEW: new_syntax

  where old_syntax refers to the syntax used in LIGGGHTS 1.5.3 and before, and new_syntax refers to the syntax used in LIGGGHTS 2.X

  atom_style sphere (formerly atom_style granular):

      OLD: atom_style granular
      NEW: atom_style sphere

  NOTE: For compatibility reasons, the old syntax can still be used in LIGGGHTS 2.0

  For details, see atom_style sphere.

  dump mesh/stl:

      OLD: dmpstl all stl 300 post/dump*.stl
      NEW: dmpstl all mesh/stl 300 post/dump*.stl

  NOTE: For compatibility reasons, the old syntax can still be used in LIGGGHTS 2.0

  dump mesh/vtk:

      OLD: dmpstl all mesh/gran/VTK 300 post/dump*.stl id
      NEW: dmpstl all mesh/vtk 300 post/dump*.stl id

  NOTE: For compatibility reasons, the old syntax can still be used in LIGGGHTS 2.0

  fix heat/gran:

      OLD: fix ID group-ID heat/gran 273.15
      NEW: fix ID group-ID heat/gran initial_temperature 273.15

      OLD: fix ID group-ID heat/gran 273.15 + activate area correction via fix property/global
      NEW: fix ID group-ID heat/gran initial_temperature 273.15 area_correction on

  fix mesh/surface (formerly fix mesh/gran):

      OLD: fix ID group-ID mesh/gran mesh.stl 1 1.0 0. 0. 0. 0. 0. 0.
      NEW: fix ID group-ID mesh/surface file mesh.stl type 1

      OLD: fix ID group-ID mesh/gran mesh.stl 1 0.001 0. 0. 0. -90. 0. 0.
      NEW: fix ID group-ID mesh/surface file mesh.stl type 1 scale 0.001 rotate axis 1. 0. 0. angle -90.

      OLD: fix ID group-ID mesh/gran mesh.stl 1 1.0 1. 2. 3. 0. 0. 0.
      NEW: fix ID group-ID mesh/surface file mesh.stl type 1 move 1. 2. 3

      OLD: fix ID group-ID mesh/gran mesh.stl 1 1.0 0. 0. 0. 0. 0. 0. conveyor 5. 0. 0.
      NEW: fix ID group-ID mesh/surface file mesh.stl type 1 surface_vel 5. 0. 0.

      OLD: fix ID group-ID mesh/gran mesh.stl 1 1.0 0. 0. 0. 0. 0. 0. rotate 0. 0. 0. 1. 0. 0. 5.
      NEW: fix ID group-ID mesh/surface file mesh.stl type 1 surface_ang_vel origin 0. 0. 0. axis  1. 0. 0. omega 5.

  For details, see fix mesh/surface.

  fix mesh/surface/stress (formerly fix mesh/gran/stressanalysis):

      OLD: fix ID group-ID mesh/gran/stressanalysis mesh.stl 1 1.0 0. 0. 0. 0. 0. 0. finnie yes
      NEW: fix ID group-ID fix mesh/surface/stress file mesh.stl type 1 wear finnie

  For details, see fix mesh/surface/stress.

  fix move/mesh (formerly fix move/mesh/gran):

      OLD: fix ID group-ID move/mesh/gran wiggle -0.1 0. 0. 0.02 cad1 1
      NEW: fix ID group-ID move/mesh mesh cad1 wiggle amplitude -0.1 0. 0. period 0.02

      OLD: fix ID group-ID move/mesh/gran rotate 0. 0. 0. 0. 0. 1. 0.05 cad1 1
      NEW: fix ID group-ID move/mesh mesh cad1 rotate origin 0. 0. 0. axis  0. 0. 1. period 0.05

      OLD: fix ID group-ID move/mesh/gran linear 20. 20. 0. cad1 1
      NEW: fix ID group-ID move/mesh mesh cad1 linear 20. 20. 0.

  NOTES:
- The trailing "1" for the old_syntax was no longer used in LIGGGHTS 1.5.3
- For compatibility reasons, the command name fix move/mesh/gran can be used in LIGGGHTS 2.0. However, the syntax has to follow the LIGGGHTS 2.0 syntax.

  For details, see fix move/mesh.

  fix wall/gran/*:

      OLD: fix ID group-ID wall/gran/hertz/history 1 0 mesh/gran 2 cad1 cad2
      NEW: fix ID group-ID wall/gran/hertz/history mesh n_meshes 2 meshes cad1 cad2

      OLD: fix ID group-ID wall/gran/hertz/history 1 0 xplane -0.5 0.5 1
      NEW: fix ID1 group-ID wall/gran/hertz/history type 1 xplane -0.5
           fix ID2 group-ID wall/gran/hertz/history type 1 xplane 0.5

      OLD: fix ID group-ID wall/gran/hertz/history 3 0 xplane -0.5 0.5 1
      NEW: fix ID1 group-ID wall/gran/hertz/history primitive type 1 xplane -0.5 rolling_friction cdt
           fix ID2 group-ID wall/gran/hertz/history primitive type 1 xplane  0.5 rolling_friction cdt

      OLD: fix ID group-ID wall/gran/hertz/history 1 1 xplane -0.5 0.5 1
      NEW: fix ID group-ID wall/gran/hertz/history primitive type 1 xplane -0.5 0.5 cohesion sjkr

      OLD: fix ID group-ID wall/gran/hertz/history 0 0 zcylinder 0.05 1
      NEW: fix ID group-ID wall/gran/hertz/history primitive type 1 zcylinder 0.05 0. 0. tangential_damping off

  NOTES:
- Same applies for hooke/history, hooke, hooke/history/simple, hertz/history/simple
- sjkr stands for 'simplified JKR (Johnson-Kendall-Roberts)' model, and cdt for 'constant directional torque' model
- styles xplane, yplane, zplane take only one arg now (the wall position), if you want two walls you have to use two fix commands
- in addition to the existing style zcylinder, there is now xcylinder and ycylinder as well
- xcylinder ycylinder and zcylinder take 3 args: the cylinder radius, and the location of the axis in the other two dimensions

  For details, see fix wall/gran.

  pair_style gran/*:

      OLD: pair_style gran/hertz/history 1 0
      NEW: pair_style gran/hertz/history

      OLD: pair_style gran/hertz/history 3 0
      NEW: pair_style gran/hertz/history rolling_friction cdt

      OLD: pair_style gran/hertz/history 1 1
      NEW: pair_style gran/hertz/history cohesion sjkr

      OLD: pair_style gran/hertz/history 0 0
      NEW: pair_style gran/hertz/history tangential_damping off

  NOTES:
- Same applies for hooke/history, hooke, hooke/history/simple, hertz/history/simple
- sjkr stands for "simplified JKR (Johnson-Kendall-Roberts)" model, and cdt for "constant directional torque" model

  For details, see pair_style gran.