c     Extern "C" declaration has the form:
c     
c  void meam_force_(int *, int *, int *, double *, int *, int *, int *, double *,
c		 int *, int *, int *, int *, double *, double *,
c		 double *, double *, double *, double *, double *, double *,
c		 double *, double *, double *, double *, double *, double *,
c		 double *, double *, double *, double *, double *, double *, int *);
c     
c     Call from pair_meam.cpp has the form:
c     
c    meam_force_(&i,&nmax,&eflag_either,&eflag_global,&eflag_atom,&vflag_atom,
c              &eng_vdwl,eatom,&ntype,type,fmap,&x[0][0],
c	       &numneigh[i],firstneigh[i],&numneigh_full[i],firstneigh_full[i],
c	       &scrfcn[offset],&dscrfcn[offset],&fcpair[offset],
c	       dgamma1,dgamma2,dgamma3,rho0,rho1,rho2,rho3,frhop,
c	       &arho1[0][0],&arho2[0][0],arho2b,&arho3[0][0],&arho3b[0][0],
c	       &t_ave[0][0],&tsq_ave[0][0],&f[0][0],&vatom[0][0],&errorflag);
c     

      subroutine meam_force(i, nmax,
     $     eflag_either, eflag_global, eflag_atom, vflag_atom,
     $     eng_vdwl, eatom, ntype, type, fmap, x,
     $     numneigh, firstneigh, numneigh_full, firstneigh_full,
     $     scrfcn, dscrfcn, fcpair, 
     $     dGamma1, dGamma2, dGamma3, rho0, rho1, rho2, rho3, fp,
     $     Arho1, Arho2, Arho2b, Arho3, Arho3b, t_ave, tsq_ave, f, 
     $     vatom, errorflag)

      use meam_data
      implicit none

      integer eflag_either, eflag_global, eflag_atom, vflag_atom
      integer nmax, ntype, type, fmap
      real*8  eng_vdwl, eatom, x
      integer numneigh, firstneigh, numneigh_full, firstneigh_full
      real*8  scrfcn, dscrfcn, fcpair
      real*8  dGamma1, dGamma2, dGamma3
      real*8  rho0, rho1, rho2, rho3, fp
      real*8  Arho1, Arho2, Arho2b
      real*8  Arho3, Arho3b
      real*8  t_ave, tsq_ave, f, vatom
      integer errorflag

      dimension eatom(nmax)
      dimension type(nmax), fmap(ntype)
      dimension x(3,nmax)
      dimension firstneigh(numneigh), firstneigh_full(numneigh_full)
      dimension scrfcn(numneigh), dscrfcn(numneigh), fcpair(numneigh)
      dimension dGamma1(nmax), dGamma2(nmax), dGamma3(nmax)
      dimension rho0(nmax), rho1(nmax), rho2(nmax), rho3(nmax), fp(nmax)
      dimension Arho1(3,nmax), Arho2(6,nmax), Arho2b(nmax)
      dimension Arho3(10,nmax), Arho3b(3,nmax)
      dimension t_ave(3,nmax), tsq_ave(3,nmax), f(3,nmax), vatom(6,nmax)

      integer i,j,jn,k,kn,kk,m,n,p,q
      integer nv2,nv3,elti,eltj,eltk,ind
      real*8 xitmp,yitmp,zitmp,delij(3),delref(3),rij2,rij,rij3
      real*8 delik(3),deljk(3),v(6),fi(3),fj(3)
      real*8 Eu,astar,astarp,third,sixth
      real*8 pp,phiforce,dUdrij,dUdsij,dUdrijm(3),force,forcem
      real*8 B,r,recip,phi,phip,rhop,a
      real*8 sij,fcij,dfcij,ds(3)
      real*8 a0,a1,a1i,a1j,a2,a2i,a2j
      real*8 a3i,a3j,a3i1,a3i2,a3j1,a3j2
      real*8 G,dG,Gbar,dGbar,gam,shpi(3),shpj(3),Z,denom
      real*8 ai,aj,ro0i,ro0j,invrei,invrej
      real*8 b0,rhoa0j,drhoa0j,rhoa0i,drhoa0i
      real*8 b1,rhoa1j,drhoa1j,rhoa1i,drhoa1i
      real*8 b2,rhoa2j,drhoa2j,rhoa2i,drhoa2i
      real*8 a3,a3a,b3,rhoa3j,drhoa3j,rhoa3i,drhoa3i
      real*8 drho0dr1,drho0dr2,drho0ds1,drho0ds2
      real*8 drho1dr1,drho1dr2,drho1ds1,drho1ds2
      real*8 drho1drm1(3),drho1drm2(3)
      real*8 drho2dr1,drho2dr2,drho2ds1,drho2ds2
      real*8 drho2drm1(3),drho2drm2(3)
      real*8 drho3dr1,drho3dr2,drho3ds1,drho3ds2
      real*8 drho3drm1(3),drho3drm2(3)
      real*8 dt1dr1,dt1dr2,dt1ds1,dt1ds2
      real*8 dt2dr1,dt2dr2,dt2ds1,dt2ds2
      real*8 dt3dr1,dt3dr2,dt3ds1,dt3ds2
      real*8 drhodr1,drhodr2,drhods1,drhods2,drhodrm1(3),drhodrm2(3)
      real*8 arg,arg1,arg2
      real*8 arg1i1,arg1j1,arg1i2,arg1j2,arg2i2,arg2j2
      real*8 arg1i3,arg1j3,arg2i3,arg2j3,arg3i3,arg3j3
      real*8 dsij1,dsij2,force1,force2
      real*8 t1i,t2i,t3i,t1j,t2j,t3j

      errorflag = 0
      third = 1.0/3.0
      sixth = 1.0/6.0

c     Compute forces atom i

      elti = fmap(type(i))
      
      if (elti.gt.0) then
        xitmp = x(1,i)
        yitmp = x(2,i)
        zitmp = x(3,i)
        
c     Treat each pair
        do jn = 1,numneigh
          
          j = firstneigh(jn)
          eltj = fmap(type(j))

          if (scrfcn(jn).ne.0.d0.and.eltj.gt.0) then
            
            sij = scrfcn(jn)*fcpair(jn)
            delij(1) = x(1,j) - xitmp
            delij(2) = x(2,j) - yitmp
            delij(3) = x(3,j) - zitmp
            rij2 = delij(1)*delij(1) + delij(2)*delij(2)
     $           + delij(3)*delij(3)
            if (rij2.lt.cutforcesq) then
              rij = sqrt(rij2)
              r = rij
              
c     Compute phi and phip
              ind = eltind(elti,eltj)
              pp = rij*rdrar + 1.0D0
              kk = pp
              kk = min(kk,nrar-1)
              pp = pp - kk
              pp = min(pp,1.0D0)
              phi = ((phirar3(kk,ind)*pp + phirar2(kk,ind))*pp 
     $             + phirar1(kk,ind))*pp + phirar(kk,ind)
              phip = (phirar6(kk,ind)*pp + phirar5(kk,ind))*pp 
     $             + phirar4(kk,ind)
              recip = 1.0d0/r
              
              if (eflag_either.ne.0) then
                if (eflag_global.ne.0) eng_vdwl = eng_vdwl + phi*sij
                if (eflag_atom.ne.0) then
                  eatom(i) = eatom(i) + 0.5*phi*sij
                  eatom(j) = eatom(j) + 0.5*phi*sij
                endif
              endif
              
c     write(1,*) "force_meamf: phi: ",phi
c     write(1,*) "force_meamf: phip: ",phip
              
c     Compute pair densities and derivatives
              invrei = 1.d0/re_meam(elti,elti)
              ai = rij*invrei - 1.d0
              ro0i = rho0_meam(elti)
              rhoa0i = ro0i*exp(-beta0_meam(elti)*ai)
              drhoa0i = -beta0_meam(elti)*invrei*rhoa0i
              rhoa1i = ro0i*exp(-beta1_meam(elti)*ai)
              drhoa1i = -beta1_meam(elti)*invrei*rhoa1i
              rhoa2i = ro0i*exp(-beta2_meam(elti)*ai)
              drhoa2i = -beta2_meam(elti)*invrei*rhoa2i
              rhoa3i = ro0i*exp(-beta3_meam(elti)*ai)
              drhoa3i = -beta3_meam(elti)*invrei*rhoa3i
              
              if (elti.ne.eltj) then
                invrej = 1.d0/re_meam(eltj,eltj)
                aj = rij*invrej - 1.d0
                ro0j = rho0_meam(eltj)
                rhoa0j = ro0j*exp(-beta0_meam(eltj)*aj)
                drhoa0j = -beta0_meam(eltj)*invrej*rhoa0j
                rhoa1j = ro0j*exp(-beta1_meam(eltj)*aj)
                drhoa1j = -beta1_meam(eltj)*invrej*rhoa1j
                rhoa2j = ro0j*exp(-beta2_meam(eltj)*aj)
                drhoa2j = -beta2_meam(eltj)*invrej*rhoa2j
                rhoa3j = ro0j*exp(-beta3_meam(eltj)*aj)
                drhoa3j = -beta3_meam(eltj)*invrej*rhoa3j
              else
                rhoa0j = rhoa0i
                drhoa0j = drhoa0i
                rhoa1j = rhoa1i
                drhoa1j = drhoa1i
                rhoa2j = rhoa2i
                drhoa2j = drhoa2i
                rhoa3j = rhoa3i
                drhoa3j = drhoa3i
              endif
              
              if (ialloy.eq.1) then
                rhoa1j = rhoa1j * t1_meam(eltj)
                rhoa2j = rhoa2j * t2_meam(eltj)
                rhoa3j = rhoa3j * t3_meam(eltj)
                rhoa1i = rhoa1i * t1_meam(elti)
                rhoa2i = rhoa2i * t2_meam(elti)
                rhoa3i = rhoa3i * t3_meam(elti)
                drhoa1j = drhoa1j * t1_meam(eltj)
                drhoa2j = drhoa2j * t2_meam(eltj)
                drhoa3j = drhoa3j * t3_meam(eltj)
                drhoa1i = drhoa1i * t1_meam(elti)
                drhoa2i = drhoa2i * t2_meam(elti)
                drhoa3i = drhoa3i * t3_meam(elti)
              endif

              nv2 = 1
              nv3 = 1
              arg1i1 = 0.d0
              arg1j1 = 0.d0
              arg1i2 = 0.d0
              arg1j2 = 0.d0
              arg1i3 = 0.d0
              arg1j3 = 0.d0
              arg3i3 = 0.d0
              arg3j3 = 0.d0
              do n = 1,3
                do p = n,3
                  do q = p,3
                    arg = delij(n)*delij(p)*delij(q)*v3D(nv3)
                    arg1i3 = arg1i3 + Arho3(nv3,i)*arg
                    arg1j3 = arg1j3 - Arho3(nv3,j)*arg
                    nv3 = nv3+1
                  enddo
                  arg = delij(n)*delij(p)*v2D(nv2)
                  arg1i2 = arg1i2 + Arho2(nv2,i)*arg
                  arg1j2 = arg1j2 + Arho2(nv2,j)*arg
                  nv2 = nv2+1
                enddo
                arg1i1 = arg1i1 + Arho1(n,i)*delij(n)
                arg1j1 = arg1j1 - Arho1(n,j)*delij(n)
                arg3i3 = arg3i3 + Arho3b(n,i)*delij(n)
                arg3j3 = arg3j3 - Arho3b(n,j)*delij(n)             
              enddo
              
c     rho0 terms
              drho0dr1 = drhoa0j * sij
              drho0dr2 = drhoa0i * sij
              
c     rho1 terms  
              a1 = 2*sij/rij              
              drho1dr1 = a1*(drhoa1j-rhoa1j/rij)*arg1i1
              drho1dr2 = a1*(drhoa1i-rhoa1i/rij)*arg1j1
              a1 = 2.d0*sij/rij
              do m = 1,3
                drho1drm1(m) = a1*rhoa1j*Arho1(m,i)
                drho1drm2(m) = -a1*rhoa1i*Arho1(m,j)
              enddo
              
c     rho2 terms
              a2 = 2*sij/rij2
              drho2dr1 = a2*(drhoa2j - 2*rhoa2j/rij)*arg1i2 
     $             - 2.d0/3.d0*Arho2b(i)*drhoa2j*sij
              drho2dr2 = a2*(drhoa2i - 2*rhoa2i/rij)*arg1j2
     $             - 2.d0/3.d0*Arho2b(j)*drhoa2i*sij
              a2 = 4*sij/rij2
              do m = 1,3
                drho2drm1(m) = 0.d0
                drho2drm2(m) = 0.d0
                do n = 1,3
                  drho2drm1(m) = drho2drm1(m) 
     $                 + Arho2(vind2D(m,n),i)*delij(n)
                  drho2drm2(m) = drho2drm2(m)
     $                 - Arho2(vind2D(m,n),j)*delij(n)
                enddo
                drho2drm1(m) = a2*rhoa2j*drho2drm1(m)
                drho2drm2(m) = -a2*rhoa2i*drho2drm2(m)
              enddo
              
c     rho3 terms
              rij3 = rij*rij2
              a3 = 2*sij/rij3
              a3a = 6.d0/5.d0*sij/rij
              drho3dr1 = a3*(drhoa3j - 3*rhoa3j/rij)*arg1i3 
     $             - a3a*(drhoa3j - rhoa3j/rij)*arg3i3
              drho3dr2 = a3*(drhoa3i - 3*rhoa3i/rij)*arg1j3 
     $             - a3a*(drhoa3i - rhoa3i/rij)*arg3j3
              a3 = 6*sij/rij3
              a3a = 6*sij/(5*rij)
              do m = 1,3
                drho3drm1(m) = 0.d0
                drho3drm2(m) = 0.d0
                nv2 = 1
                do n = 1,3
                  do p = n,3
                    arg = delij(n)*delij(p)*v2D(nv2)
                    drho3drm1(m) = drho3drm1(m)
     $                   + Arho3(vind3D(m,n,p),i)*arg
                    drho3drm2(m) = drho3drm2(m)
     $                   + Arho3(vind3D(m,n,p),j)*arg
                    nv2 = nv2 + 1
                  enddo
                enddo
                drho3drm1(m) = (a3*drho3drm1(m) - a3a*Arho3b(m,i))
     $               *rhoa3j
                drho3drm2(m) = (-a3*drho3drm2(m) + a3a*Arho3b(m,j))
     $               *rhoa3i
              enddo

c     Compute derivatives of weighting functions t wrt rij
              t1i = t_ave(1,i)
              t2i = t_ave(2,i)
              t3i = t_ave(3,i)
              t1j = t_ave(1,j)
              t2j = t_ave(2,j)
              t3j = t_ave(3,j)

              if (ialloy.eq.1) then

                a1i = 0.d0
                a1j = 0.d0
                a2i = 0.d0
                a2j = 0.d0
                a3i = 0.d0
                a3j = 0.d0
                if ( tsq_ave(1,i) .ne. 0.d0 ) then
                  a1i = drhoa0j*sij/tsq_ave(1,i)
                endif
                if ( tsq_ave(1,j) .ne. 0.d0 ) then
                  a1j = drhoa0i*sij/tsq_ave(1,j)
                endif
                if ( tsq_ave(2,i) .ne. 0.d0 ) then
                  a2i = drhoa0j*sij/tsq_ave(2,i)
                endif
                if ( tsq_ave(2,j) .ne. 0.d0 ) then
                  a2j = drhoa0i*sij/tsq_ave(2,j)
                endif
                if ( tsq_ave(3,i) .ne. 0.d0 ) then
                  a3i = drhoa0j*sij/tsq_ave(3,i)
                endif
                if ( tsq_ave(3,j) .ne. 0.d0 ) then
                  a3j = drhoa0i*sij/tsq_ave(3,j)
                endif

                dt1dr1 = a1i*(t1_meam(eltj)-t1i*t1_meam(eltj)**2)
                dt1dr2 = a1j*(t1_meam(elti)-t1j*t1_meam(elti)**2)
                dt2dr1 = a2i*(t2_meam(eltj)-t2i*t2_meam(eltj)**2)
                dt2dr2 = a2j*(t2_meam(elti)-t2j*t2_meam(elti)**2)
                dt3dr1 = a3i*(t3_meam(eltj)-t3i*t3_meam(eltj)**2)
                dt3dr2 = a3j*(t3_meam(elti)-t3j*t3_meam(elti)**2)

              else if (ialloy.eq.2) then
                
                dt1dr1 = 0.d0
                dt1dr2 = 0.d0
                dt2dr1 = 0.d0
                dt2dr2 = 0.d0
                dt3dr1 = 0.d0
                dt3dr2 = 0.d0

              else

                ai = 0.d0
                if( rho0(i) .ne. 0.d0 ) then
                  ai = drhoa0j*sij/rho0(i)
                end if
                aj = 0.d0
                if( rho0(j) .ne. 0.d0 ) then
                  aj = drhoa0i*sij/rho0(j)
                end if

                dt1dr1 = ai*(t1_meam(eltj)-t1i)
                dt1dr2 = aj*(t1_meam(elti)-t1j)
                dt2dr1 = ai*(t2_meam(eltj)-t2i)
                dt2dr2 = aj*(t2_meam(elti)-t2j)
                dt3dr1 = ai*(t3_meam(eltj)-t3i)
                dt3dr2 = aj*(t3_meam(elti)-t3j)
                
              endif

c     Compute derivatives of total density wrt rij, sij and rij(3)
              call get_shpfcn(shpi,lattce_meam(elti,elti))
              call get_shpfcn(shpj,lattce_meam(eltj,eltj))
              drhodr1 = dGamma1(i)*drho0dr1
     $             + dGamma2(i)*
     $             (dt1dr1*rho1(i)+t1i*drho1dr1
     $             + dt2dr1*rho2(i)+t2i*drho2dr1
     $             + dt3dr1*rho3(i)+t3i*drho3dr1)
     $             - dGamma3(i)*
     $             (shpi(1)*dt1dr1+shpi(2)*dt2dr1+shpi(3)*dt3dr1)
              drhodr2 = dGamma1(j)*drho0dr2
     $             + dGamma2(j)*
     $             (dt1dr2*rho1(j)+t1j*drho1dr2
     $             + dt2dr2*rho2(j)+t2j*drho2dr2
     $             + dt3dr2*rho3(j)+t3j*drho3dr2)
     $             - dGamma3(j)*
     $             (shpj(1)*dt1dr2+shpj(2)*dt2dr2+shpj(3)*dt3dr2)
              do m = 1,3
                drhodrm1(m) = 0.d0
                drhodrm2(m) = 0.d0
                drhodrm1(m) = dGamma2(i)*
     $               (t1i*drho1drm1(m)
     $               + t2i*drho2drm1(m)
     $               + t3i*drho3drm1(m))
                drhodrm2(m) = dGamma2(j)*
     $               (t1j*drho1drm2(m)
     $               + t2j*drho2drm2(m)
     $               + t3j*drho3drm2(m))
              enddo

c     Compute derivatives wrt sij, but only if necessary
              if (dscrfcn(jn).ne.0.d0) then
                drho0ds1 = rhoa0j
                drho0ds2 = rhoa0i
                a1 = 2.d0/rij
                drho1ds1 = a1*rhoa1j*arg1i1
                drho1ds2 = a1*rhoa1i*arg1j1
                a2 = 2.d0/rij2
                drho2ds1 = a2*rhoa2j*arg1i2 
     $               - 2.d0/3.d0*Arho2b(i)*rhoa2j
                drho2ds2 = a2*rhoa2i*arg1j2 
     $               - 2.d0/3.d0*Arho2b(j)*rhoa2i
                a3 = 2.d0/rij3
                a3a = 6.d0/(5.d0*rij)
                drho3ds1 = a3*rhoa3j*arg1i3 - a3a*rhoa3j*arg3i3
                drho3ds2 = a3*rhoa3i*arg1j3 - a3a*rhoa3i*arg3j3

                if (ialloy.eq.1) then
                  
                  a1i = 0.d0
                  a1j = 0.d0
                  a2i = 0.d0
                  a2j = 0.d0
                  a3i = 0.d0
                  a3j = 0.d0
                  if ( tsq_ave(1,i) .ne. 0.d0 ) then
                    a1i = rhoa0j/tsq_ave(1,i)
                  endif
                  if ( tsq_ave(1,j) .ne. 0.d0 ) then
                    a1j = rhoa0i/tsq_ave(1,j)
                  endif
                  if ( tsq_ave(2,i) .ne. 0.d0 ) then
                    a2i = rhoa0j/tsq_ave(2,i)
                  endif
                  if ( tsq_ave(2,j) .ne. 0.d0 ) then
                    a2j = rhoa0i/tsq_ave(2,j)
                  endif
                  if ( tsq_ave(3,i) .ne. 0.d0 ) then
                    a3i = rhoa0j/tsq_ave(3,i)
                  endif
                  if ( tsq_ave(3,j) .ne. 0.d0 ) then
                    a3j = rhoa0i/tsq_ave(3,j)
                  endif

                  dt1ds1 = a1i*(t1_meam(eltj)-t1i*t1_meam(eltj)**2)
                  dt1ds2 = a1j*(t1_meam(elti)-t1j*t1_meam(elti)**2)
                  dt2ds1 = a2i*(t2_meam(eltj)-t2i*t2_meam(eltj)**2)
                  dt2ds2 = a2j*(t2_meam(elti)-t2j*t2_meam(elti)**2)
                  dt3ds1 = a3i*(t3_meam(eltj)-t3i*t3_meam(eltj)**2)
                  dt3ds2 = a3j*(t3_meam(elti)-t3j*t3_meam(elti)**2)

                else if (ialloy.eq.2) then

                  dt1ds1 = 0.d0
                  dt1ds2 = 0.d0
                  dt2ds1 = 0.d0
                  dt2ds2 = 0.d0
                  dt3ds1 = 0.d0
                  dt3ds2 = 0.d0

                else

                  ai = 0.d0
                  if( rho0(i) .ne. 0.d0 ) then
                    ai = rhoa0j/rho0(i)
                  end if
                  aj = 0.d0
                  if( rho0(j) .ne. 0.d0 ) then
                    aj = rhoa0i/rho0(j)
                  end if
                  
                  dt1ds1 = ai*(t1_meam(eltj)-t1i)
                  dt1ds2 = aj*(t1_meam(elti)-t1j)
                  dt2ds1 = ai*(t2_meam(eltj)-t2i)
                  dt2ds2 = aj*(t2_meam(elti)-t2j)
                  dt3ds1 = ai*(t3_meam(eltj)-t3i)
                  dt3ds2 = aj*(t3_meam(elti)-t3j)

                endif

                drhods1 = dGamma1(i)*drho0ds1
     $               + dGamma2(i)*
     $               (dt1ds1*rho1(i)+t1i*drho1ds1
     $               + dt2ds1*rho2(i)+t2i*drho2ds1
     $               + dt3ds1*rho3(i)+t3i*drho3ds1)
     $               - dGamma3(i)*
     $               (shpi(1)*dt1ds1+shpi(2)*dt2ds1+shpi(3)*dt3ds1)
                drhods2 = dGamma1(j)*drho0ds2
     $               + dGamma2(j)*
     $               (dt1ds2*rho1(j)+t1j*drho1ds2
     $               + dt2ds2*rho2(j)+t2j*drho2ds2
     $               + dt3ds2*rho3(j)+t3j*drho3ds2)
     $               - dGamma3(j)*
     $               (shpj(1)*dt1ds2+shpj(2)*dt2ds2+shpj(3)*dt3ds2)
              endif

c     Compute derivatives of energy wrt rij, sij and rij(3)
              dUdrij = phip*sij
     $             + fp(i)*drhodr1 + fp(j)*drhodr2
              dUdsij = 0.d0
              if (dscrfcn(jn).ne.0.d0) then
                dUdsij = phi
     $               + fp(i)*drhods1 + fp(j)*drhods2
              endif
              do m = 1,3
                dUdrijm(m) = fp(i)*drhodrm1(m) + fp(j)*drhodrm2(m)
              enddo
              
c     Add the part of the force due to dUdrij and dUdsij

              force = dUdrij*recip + dUdsij*dscrfcn(jn)
              do m = 1,3
                forcem = delij(m)*force + dUdrijm(m)
                f(m,i) = f(m,i) + forcem
                f(m,j) = f(m,j) - forcem
              enddo

c     Tabulate per-atom virial as symmetrized stress tensor

              if (vflag_atom.ne.0) then
                fi(1) = delij(1)*force + dUdrijm(1)
                fi(2) = delij(2)*force + dUdrijm(2)
                fi(3) = delij(3)*force + dUdrijm(3)
                v(1) = -0.5 * (delij(1) * fi(1))
                v(2) = -0.5 * (delij(2) * fi(2))
                v(3) = -0.5 * (delij(3) * fi(3))
                v(4) = -0.25 * (delij(1)*fi(2) + delij(2)*fi(1))
                v(5) = -0.25 * (delij(1)*fi(3) + delij(3)*fi(1))
                v(6) = -0.25 * (delij(2)*fi(3) + delij(3)*fi(2))

                vatom(1,i) = vatom(1,i) + v(1)
                vatom(2,i) = vatom(2,i) + v(2)
                vatom(3,i) = vatom(3,i) + v(3)
                vatom(4,i) = vatom(4,i) + v(4)
                vatom(5,i) = vatom(5,i) + v(5)
                vatom(6,i) = vatom(6,i) + v(6)
                vatom(1,j) = vatom(1,j) + v(1)
                vatom(2,j) = vatom(2,j) + v(2)
                vatom(3,j) = vatom(3,j) + v(3)
                vatom(4,j) = vatom(4,j) + v(4)
                vatom(5,j) = vatom(5,j) + v(5)
                vatom(6,j) = vatom(6,j) + v(6)
              endif

c     Now compute forces on other atoms k due to change in sij

              if (sij.eq.0.d0.or.sij.eq.1.d0) goto 100
              do kn = 1,numneigh_full
                k = firstneigh_full(kn)
                eltk = fmap(type(k))
                if (k.ne.j.and.eltk.gt.0) then
                  call dsij(i,j,k,jn,nmax,numneigh,rij2,dsij1,dsij2,
     $                 ntype,type,fmap,x,scrfcn,fcpair)
                  if (dsij1.ne.0.d0.or.dsij2.ne.0.d0) then
                    force1 = dUdsij*dsij1
                    force2 = dUdsij*dsij2
                    do m = 1,3
                      delik(m) = x(m,k) - x(m,i)
                      deljk(m) = x(m,k) - x(m,j)
                    enddo
                    do m = 1,3
                      f(m,i) = f(m,i) + force1*delik(m)
                      f(m,j) = f(m,j) + force2*deljk(m)
                      f(m,k) = f(m,k) - force1*delik(m)
     $                     - force2*deljk(m)
                    enddo

c     Tabulate per-atom virial as symmetrized stress tensor

                    if (vflag_atom.ne.0) then
                      fi(1) = force1*delik(1)
                      fi(2) = force1*delik(2)
                      fi(3) = force1*delik(3)
                      fj(1) = force2*deljk(1)
                      fj(2) = force2*deljk(2)
                      fj(3) = force2*deljk(3)
                      v(1) = -third * (delik(1)*fi(1) + deljk(1)*fj(1))
                      v(2) = -third * (delik(2)*fi(2) + deljk(2)*fj(2))
                      v(3) = -third * (delik(3)*fi(3) + deljk(3)*fj(3))
                      v(4) = -sixth * (delik(1)*fi(2) + deljk(1)*fj(2) +
     $                     delik(2)*fi(1) + deljk(2)*fj(1))
                      v(5) = -sixth * (delik(1)*fi(3) + deljk(1)*fj(3) +
     $                     delik(3)*fi(1) + deljk(3)*fj(1))
                      v(6) = -sixth * (delik(2)*fi(3) + deljk(2)*fj(3) +
     $                      delik(3)*fi(2) + deljk(3)*fj(2))

                      vatom(1,i) = vatom(1,i) + v(1)
                      vatom(2,i) = vatom(2,i) + v(2)
                      vatom(3,i) = vatom(3,i) + v(3)
                      vatom(4,i) = vatom(4,i) + v(4)
                      vatom(5,i) = vatom(5,i) + v(5)
                      vatom(6,i) = vatom(6,i) + v(6)
                      vatom(1,j) = vatom(1,j) + v(1)
                      vatom(2,j) = vatom(2,j) + v(2)
                      vatom(3,j) = vatom(3,j) + v(3)
                      vatom(4,j) = vatom(4,j) + v(4)
                      vatom(5,j) = vatom(5,j) + v(5)
                      vatom(6,j) = vatom(6,j) + v(6)
                      vatom(1,k) = vatom(1,k) + v(1)
                      vatom(2,k) = vatom(2,k) + v(2)
                      vatom(3,k) = vatom(3,k) + v(3)
                      vatom(4,k) = vatom(4,k) + v(4)
                      vatom(5,k) = vatom(5,k) + v(5)
                      vatom(6,k) = vatom(6,k) + v(6)
                    endif

                  endif
                endif
c     end of k loop
              enddo
            endif
 100        continue
          endif
c     end of j loop
        enddo

c     else if elti=0, this is not a meam atom
      endif
      
      return
      end

      subroutine phif(elti,eltj,rij,phi,phip)
      use meam_data
      implicit none

      integer elti,eltj,ind,kk
      real*8 rij,pp,phi,phip
      if (rij.lt.cutforce) then
         ind = eltind(elti,eltj)
         pp = rij*rdrar + 1.0D0
         kk = pp
         kk = min(kk,nrar-1)
         pp = pp - kk
         pp = min(pp,1.0D0)
         phi = ((phirar3(kk,ind)*pp + phirar2(kk,ind))*pp
     $        + phirar1(kk,ind))*pp + phirar(kk,ind)      
         phip = (phirar6(kk,ind)*pp + phirar5(kk,ind))*pp
     $        + phirar4(kk,ind)
      else
         phi = 0.d0
         phip = 0.d0
      endif
      return
      end

