!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!! !!!!! !!!!! 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 : Pair_Morse_Shifted_GirifalcoWeizer_LowCutoff_Rb__MO_754498969542_001 Supported species : Rb random seed = 13 lattice constant (orig) = 3.000 perturbation amplitude = 0.300 number unit cells per side = 2 ------------------------------------------------------------------------------------------------------------------------- MONOATOMIC STRUCTURE -- Species = Rb (Configuration in file "config-Rb.xyz") ------------------------------------------------------------------------------------------------------------------------- Translation vector = -2.53291801e+00 -1.63492038e+00 -8.83722850e-01 Energy requirement: V(-(r_1+c),...,-(r_N+c)) = V(r_1,...,r_N), where r_i is the position of atom i, V is the potential energy, and c is a translation vector. V(-(r_1+c),...,-(r_N+c)) = 101.087397259 V(r_1+c,...,r_N+c) = 101.087397259 V(r_1,...,r_N) = 101.087397259 Forces requirement: f_i(-(r_1+c),...,-(r_N+c)) = -f_i(r_1,...,r_N), where r_i is the position of atom i, f_i is the force on atom i, and c is a translation vector. i f_i(-(r_1+c),...,-(r_N+c)) -f_i(r_1,...,r_N) ------------------------------------------------------------------------------------------------------------------------- 0 4.05137799e+00 2.94887623e+00 3.40254080e+00 | 4.05137799e+00 2.94887623e+00 3.40254080e+00 1 2.97231585e+00 1.58129554e+00 1.71314657e+00 | 2.97231585e+00 1.58129554e+00 1.71314657e+00 2 -2.55477774e+00 6.22778181e+00 6.64479178e+00 | -2.55477774e+00 6.22778181e+00 6.64479178e+00 3 -8.47576591e+00 1.25280270e+00 2.68311668e+00 | -8.47576591e+00 1.25280270e+00 2.68311668e+00 4 6.25774301e+00 -1.45421177e+00 4.13128455e+00 | 6.25774301e+00 -1.45421177e+00 4.13128455e+00 5 3.15677302e+00 -8.45705076e+00 1.73458673e+00 | 3.15677302e+00 -8.45705076e+00 1.73458673e+00 6 -3.10897389e+00 -1.88849053e+00 8.36693491e+00 | -3.10897389e+00 -1.88849053e+00 8.36693491e+00 7 -4.62880812e+00 -4.29093667e+00 1.50846468e+00 | -4.62880812e+00 -4.29093667e+00 1.50846468e+00 8 5.01887000e+00 4.49555225e+00 -2.75273508e+00 | 5.01887000e+00 4.49555225e+00 -2.75273508e+00 9 2.24472768e+00 2.10985829e+00 -7.33296575e+00 | 2.24472768e+00 2.10985829e+00 -7.33296575e+00 10 -2.46199699e+00 7.71122207e+00 -2.58614592e+00 | -2.46199699e+00 7.71122207e+00 -2.58614592e+00 11 -5.83117650e+00 1.95438294e+00 -4.44228414e+00 | -5.83117650e+00 1.95438294e+00 -4.44228414e+00 12 7.09770715e+00 -1.52457187e+00 -2.27123994e+00 | 7.09770715e+00 -1.52457187e+00 -2.27123994e+00 13 2.02302021e+00 -4.85970306e+00 -4.64364152e+00 | 2.02302021e+00 -4.85970306e+00 -4.64364152e+00 14 -1.76065914e+00 -2.66010630e+00 -2.46574575e+00 | -1.76065914e+00 -2.66010630e+00 -2.46574575e+00 15 -4.00037662e+00 -3.14670087e+00 -3.69010861e+00 | -4.00037662e+00 -3.14670087e+00 -3.69010861e+00 ------------------------------------------------------------------------------------------------------------------------- PASS: Energies and forces are the same to within a relative error of 1e-08 ------------------------------------------------------------------------------------------------------------------------- ========================================================================================================================= To pass this verification check the model must be invariant with respect to translation and have inversion symmetry about the origin for all configurations it was able to compute. Grade: P Comment: Model energy has inversion symmetry for all configurations the model was able to compute.