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