Parameters of vdW forcefield: C6(Jnm^6/mol), R0(A)

tags=(/'H ','He','Li','Be','B ','C ','N ','O ','F ','Ne',&

'Na','Mg','Al','Si','P ','S ','Cl','Ar','K ','Ca',&

'Sc','Ti','V ','Cr','Mn','Fe','Co','Ni','Cu','Zn',&

'Ga','Ge','As','Se','Br','Kr','Rb','Sr',&

'Y ','Zr','Nb','Mo','Tc','Ru','Rh','Pd','Ag','Cd',&

'In','Sn','Sb','Te','I ','Xe','X ', &

'Cs','Ba','La','Ce','Pr','Nd','Pm',&

'Sm','Eu','Gd',&

'Tb','Dy','Ho','Er','Tm','Yb','Lu',&

'Hf','Ta','W ','Re','Os','Ir','Pt','Au','Hg',&

'Tl','Pb','Bi','Po','At','Rn'/)

cc=(/0.14,0.08,1.61,1.61,3.13,1.75,1.23,0.70,0.75,0.63,&

5.71,5.71,10.79,9.23,7.84,5.57,5.07,4.61,10.8,10.8,&

10.8,10.8,10.8,10.8,10.8,10.8,10.8,10.8,10.8,10.8,&

16.99,17.10,16.37,12.64,12.47,12.01,24.67,24.67,&

24.67,24.67,24.67,24.67,24.67,24.67,24.67,24.67,24.67,24.67,&

37.32,38.71,38.44,31.74,31.50,29.99,29.99, &

315.275,226.994,176.252,140.68,140.68,140.68,140.68,&

140.68,140.68,140.68, &

140.68,140.68,140.68,140.68,140.68,140.68,140.68, &

105.112,81.24,81.24,81.24,81.24,81.24,81.24,81.24,57.364,&

57.254,63.162,63.540,55.283,57.171,56.64/)

r0=(/1.001,1.012,0.825,1.408,1.485,1.452,1.397,1.342,1.287,1.243,&

1.144,1.364,1.639,1.716,1.705,1.683,1.639,1.595,1.485,1.474,&

1.562,1.562,1.562,1.562,1.562,1.562,1.562,1.562,1.562,1.562,&

1.650,1.727,1.760,1.771,1.749,1.727,1.628,1.606,&

1.639,1.639,1.639,1.639,1.639,1.639,1.639,1.639,1.639,1.639,&

1.672,1.804,1.881,1.892,1.892,1.881,1.881,&

1.802,1.762,1.720,1.753,1.753,1.753,1.753,&

1.753,1.753,1.753,&

1.753,1.753,1.753,1.753,1.753,1.753,1.753,&

1.788,1.772,1.772,1.772,1.772,1.772,1.772,1.772,1.758,&

1.989,1.944,1.898,2.005,1.991,1.924/)

Manasi Mahabal how did you get this value ? could you please elaborate ?