!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!! !!!!!
!!!!! VERIFICATION CHECK: vc-inversion-symmetry !!!!!
!!!!! !!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Description: Check whether a model is invariant with respect to the inversion
operation where each atom is moved along a straight line through
the inversion center to a point of equal distance on the other
side. This is satisfied for all inversion centers if the model is
invariant to rigid-body translation, and has inversion symmetry
about the origin. Invariance symmetry is expected from the
properties of the quantum mechanics Hamiltonian operator. It should
be true for any model that does not depend on an external field.
The check is performed for a randomly distorted non-periodic body-
centered cubic (BCC) cube base structure. Separate configurations
are tested for each species supported by the model, as well as one
containing a random distribution of all species. The energy and
forces of each configuration are compared with those of the same
configuration translated in a random direction by an irrational
distance and then inverted through the origin. The energies must be
the same and the forces must change sign. The verification check
will pass if the energy of all configurations that the model is
able to compute pass both tests. Configurations used for testing
are provided as auxiliary files.
Author: Ellad Tadmor
-------------------------------------------------------------------------------------------------------------------------
Results for KIM Model : MEAM_2NN_GaInN__MO_117938381510_001
Supported species : Ga In N
random seed = 13
lattice constant (orig) = 3.000
perturbation amplitude = 0.300
number unit cells per side = 2
-------------------------------------------------------------------------------------------------------------------------