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can somebody help ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg127331] can somebody help ?
  • From: raj kumar <rajesh7796gm at gmail.com>
  • Date: Tue, 17 Jul 2012 01:32:25 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • Delivered-to: mathgroup-newout@smc.vnet.net
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dear esteemed members of the forum,
hello from malaysia
i have this workable code for a scattering process called
HKrScattering.See below.Given a particular value of say l=1 and an
energy value of say En =2, and nsteps=1000,  the code gives the
correct result for the  phase shift.
however, i would like to generate a set of values for the phase shift
for different values of l, say for l=0 to l=5 for En=2.

I have tried using a do loop for this purpose but have not been able
to get correct results so far.

can anybody please help?
will appreciate your contribution enormously!
cheers
rk


j[l_, z_] := Sqrt[\[Pi]/2 z] BesselJ[l, z];
n[l_, z_] := Sqrt[\[Pi]/2 z] BesselY[l, z];

HKrScattering[l_, En_, nsteps_] :=
 Module[{meV, \[Angstrom], \[Sigma], \[Mu], \[Lambda], k, s,
   scat, \[Delta]},

  meV =  1./(27.3 * 1000.);
  en = En*meV;
  \[Angstrom] =  1/0.52 ;
  \[Sigma] = 3.57 \[Angstrom];
  \[Epsilon] = 5.9 meV ;
  V[r_] := \[Epsilon] ( (\[Sigma]/r)^12 - 2 (\[Sigma]/r)^6);
  \[Mu] = (mH  mKr)/(mH + mKr) /. {mH -> 1836 , mKr -> 1836*136};
  \[Lambda] = 2 \[Pi]/Sqrt[2 \[Mu] en] // N;
  k = 2 \[Pi]/\[Lambda];
  (*Print["\[Lambda]= ",\[Lambda]]*);
  s = 5 \[Lambda]/nsteps;
  x = {0.5 \[Sigma], 0.5 \[Sigma] + s};
  \[Psi] = {0.0, 0.0001};
  F[r_] := 2 \[Mu] ( V[r] + 1/(2 \[Mu] r^2) l (l + 1) - en);
  Do[
   \[Psi]m = \[Psi][[n - 1]];
   \[Psi]n = \[Psi][[n]];
   xm = x[[n - 1]];
   xn = x[[n]];
   xp = xn + s;
   x = Append[x, xp];
   Fn = F[xn];
   Fp = F[xp];
   Fm = F[
     xm]; \[Psi]p  = (
      2. \[Psi]n - \[Psi]m +
       s^2/12. (10. Fn  \[Psi]n + Fm  \[Psi]m))/(1. - s^2/12. Fp);
   \[Psi] = Append[\[Psi], \[Psi]p],
   {n , 2, nsteps}
   ] ;
  \[Psi] = \[Psi]/Max[\[Psi]];
  scat = Transpose[{x, \[Psi]}];
  nmax = Length[scat];
  {r1, u1} = scat[[nmax]];
  {r2, u2} = scat[[nmax - 1]];
  K = (r1 u2)/(r2 u1);

  j1 = j[l, k r1];
  j2 = j[l, k r2];
  n1 = n[l, k r1];
  n2 = n[l, k r2];
  \[Delta] =
   ArcTan[ (K j1 - j2)/(K n1 - n2)];(*finding the phase shift*)
  Print[\[Delta]]
  (*Return[{scat,\[Delta]}*)]



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