double RNordio(double f, double S, double A0, double A1, double A2, double Dz, double Dx)

{

double JRotNordio_();

double y;

double J1;

double J2;

double w;

/** eq. 7.61 Dong's Book 2nd ed **/

/** beta(mL,mM) from A131 Supporting Info or Fig. 7.1 Dong's Book **/

/** c(mL,mM) instead of k(mL,mM), Dong's Book eq. 7.61 and 1988-JCP88pp1443 **/

w=2*pi*f;

J1=JRotNordio_(1,w,S,A0,A1,A2,Dz,Dx);

J2=JRotNordio_(2,w,S,A0,A1,A2,Dz,Dx);

y=Arot*(J1+J2);

// printf("Relax_rate = %le", y);

return y;

}