A local orthogonal transformation that transforms any centrosymmetric (CS) matrix of fourth order to the X form is found. A picewise-analytic-numerical formula Q=min{Q_pi/2,Q_theta,Q_0}, where Q_pi/2 and Q_0 are analytical expressions and the branch
Q_{theta} is found by numerical searching the optimal measurement angle thetain(0,pi/2), is proposed to calculate the quantum discord Q of general X state. The developed approaches are applied to a quantitative description of recently predicted flickerings (periodic birth and death) of the quantum-information pair correlation between nuclear 1/2 spin of atoms or molecules of a gas (for examples Xe^129) in a finite asymmetric volume in the presence of a strong magnetic field.
