c2v,        xsec
 -2.0, 0.046312139
-1.75, 0.039196581
 -1.5, 0.032703183
-1.25, 0.026831954
 -1.0, 0.021582891
-0.75, 0.016955992
 -0.5, 0.012951258
-0.25, 0.009568690
  0.0, 0.006808286
  0.1, 0.005878330
  0.2, 0.005047921
  0.3, 0.004317059
  0.4, 0.003685743
  0.5, 0.003153974
  0.6, 0.002721750
  0.7, 0.002389073
  0.8, 0.002155943
  0.9, 0.002022359
  1.0, 0.001988322
  1.1, 0.002053831
  1.2, 0.002218886
  1.3, 0.002483488
  1.4, 0.002847636
  1.5, 0.003311331
  1.6, 0.003874572
  1.7, 0.004537359
  1.8, 0.005299693
  1.9, 0.006161574
  2.0, 0.007123000
 2.25, 0.009962083
  2.5, 0.013423331
 2.75, 0.017506742
  3.0, 0.022212321
 3.25, 0.027540064
  3.5, 0.033489972
 3.75, 0.040062042
  4.0, 0.047256281