source/cluster/wham/src/intcor.f

   1 C
   2 C------------------------------------------------------------------------------
   3 C
   4       double precision function alpha(i1,i2,i3)
   5 c
   6 c  Calculates the planar angle between atoms (i1), (i2), and (i3).
   7 c
   8       implicit real*8 (a-h,o-z)
   9       include 'DIMENSIONS'
  10       include 'COMMON.GEO'
  11       include 'COMMON.CHAIN'
  12       x12=c(1,i1)-c(1,i2)
  13       x23=c(1,i3)-c(1,i2)
  14       y12=c(2,i1)-c(2,i2)
  15       y23=c(2,i3)-c(2,i2)
  16       z12=c(3,i1)-c(3,i2)
  17       z23=c(3,i3)-c(3,i2)
  18       vnorm=dsqrt(x12*x12+y12*y12+z12*z12)
  19       wnorm=dsqrt(x23*x23+y23*y23+z23*z23)
  20       scalar=(x12*x23+y12*y23+z12*z23)/(vnorm*wnorm)
  21       alpha=arcos(scalar)
  22       return
  23       end
  24 C
  25 C------------------------------------------------------------------------------
  26 C
  27       double precision function beta(i1,i2,i3,i4)
  28 c
  29 c  Calculates the dihedral angle between atoms (i1), (i2), (i3) and (i4)
  30 c
  31       implicit real*8 (a-h,o-z)
  32       include 'DIMENSIONS'
  33       include 'COMMON.GEO'
  34       include 'COMMON.CHAIN'
  35       x12=c(1,i1)-c(1,i2)
  36       x23=c(1,i3)-c(1,i2)
  37       x34=c(1,i4)-c(1,i3)
  38       y12=c(2,i1)-c(2,i2)
  39       y23=c(2,i3)-c(2,i2)
  40       y34=c(2,i4)-c(2,i3)
  41       z12=c(3,i1)-c(3,i2)
  42       z23=c(3,i3)-c(3,i2)
  43       z34=c(3,i4)-c(3,i3)
  44 cd    print '(2i3,3f10.5)',i1,i2,x12,y12,z12
  45 cd    print '(2i3,3f10.5)',i2,i3,x23,y23,z23
  46 cd    print '(2i3,3f10.5)',i3,i4,x34,y34,z34
  47       wx=-y23*z34+y34*z23
  48       wy=x23*z34-z23*x34
  49       wz=-x23*y34+y23*x34
  50       wnorm=dsqrt(wx*wx+wy*wy+wz*wz)
  51       vx=y12*z23-z12*y23
  52       vy=-x12*z23+z12*x23
  53       vz=x12*y23-y12*x23
  54       vnorm=dsqrt(vx*vx+vy*vy+vz*vz)
  55       if (vnorm.gt.1.0D-13 .and. wnorm.gt.1.0D-13) then
  56       scalar=(vx*wx+vy*wy+vz*wz)/(vnorm*wnorm)
  57       if (dabs(scalar).gt.1.0D0)
  58      &scalar=0.99999999999999D0*scalar/dabs(scalar)
  59       angle=dacos(scalar)
  60 cd    print '(2i4,10f7.3)',i2,i3,vx,vy,vz,wx,wy,wz,vnorm,wnorm,
  61 cd   &scalar,angle
  62       else
  63       angle=pi
  64       endif
  65 c     if (angle.le.0.0D0) angle=pi+angle
  66       tx=vy*wz-vz*wy
  67       ty=-vx*wz+vz*wx
  68       tz=vx*wy-vy*wx
  69       scalar=tx*x23+ty*y23+tz*z23
  70       if (scalar.lt.0.0D0) angle=-angle
  71       beta=angle
  72       return
  73       end
  74 C
  75 C------------------------------------------------------------------------------
  76 C
  77       function dist(i1,i2)
  78 c
  79 c  Calculates the distance between atoms (i1) and (i2).
  80 c
  81       implicit real*8 (a-h,o-z)
  82       include 'DIMENSIONS'
  83       include 'COMMON.GEO'
  84       include 'COMMON.CHAIN'
  85       x12=c(1,i1)-c(1,i2)
  86       y12=c(2,i1)-c(2,i2)
  87       z12=c(3,i1)-c(3,i2)
  88       dist=dsqrt(x12*x12+y12*y12+z12*z12)
  89       return
  90       end
  91 C