+c 6/22/2021 AL: alpha_GB: parameter to switch between the GB SC-SC
+c interaction potential and the all-repulsive potential with singularity
+c at zero site-site distance
+ call reada(controlcard,'ALPHA_GB',alpha_GB,1.0d-2)
+ alpha_GB1 = 1.0d0+1.0d0/alpha_GB
+ write (iout,*) "alpha_GB",alpha_GB," alpha_GB1",alpha_GB1