This example reproduces the 2010 study of the shockwave structure in
a fluid of Holian et al.[1]

It runs a non-equilibrium molecular dynamics simulations of strong
shockwave propagation in a fluid.  The potential is the smoothly
truncated cubic spline Lennard-Jones proposed by Holian and Ravelo
because of its combination of computational efficiency, qualitative
realism, and energy conservation. The same potential has also been
used to study shockwaves in solids.[2]

The main output is the estimated shock speed as a function of time in
log.lammps, estimated from the change in momentum.  Except for
non-steady state values at the start, it averages close to the value
of 45.2 reported by Holian et al.

A secondary output is the collisional velocity correlation function
(CVCF) in cvcf.dat.

In order to run this example, LAMMPS must be compiled with the
EXTRA-PAIR and EXTRA-COMPUTE packages. It also requires the history
keywords that were added to fix store/state and compute property/atom
on 06/23/2026.

[1] Holian, Mareschal, and Ravelo, J. Chem. Phys. 133, 114502 (2010).
[2] Ravelo, Holian, Germann and Lomdahl, Phys Rev B, 70, 014103 (2004).
