FCC Cluster

%function [Xcoord,Ycoord,Zcoord] = fcc_cluster(L,M,a)
%generates coordinates of atoms inside fcc-cluster (face-centered-cubic)
%with cuboctatruncated shape (hovewer one can change from {111} to {110} truncation)
%it's arguments: L,M - parameters of cluster (L - size of the cluster,
%number of unit cells along three mutually perpendicular directions
%commensurate with lattice parameter, M - truncation degree, how many planes
%corresponding to the truncation remain in cluster)
%a - lattice parameter
%output parameters: Xcoord, Ycoord, Zcoord - coordinates of atoms