C DDINQT    SOURCE    CHAT      05/01/12    22:37:56     5004           

      SUBROUTINE DERDERINVARIPQT (SIG,Q_SS,T_SS,N)
      IMPLICIT INTEGER(I-N)
      integer n,i,j
      real*8    sig(n),q_ss(6,6),t_ss(6,6),q,t,tolt,aux0,aux1,aux2,
     .          aux3,aux4,aux5,aux6,pijkl(6,6),wijkl(6,6),cst,snt,
     .          I_s(6),J2_s(6),J3_s(6)
      call Invari_q(sig,n,q)
      if (q.lt.1.D-8) then
           do i=1,6
           do j=1,6
             q_ss(i,j)=0.D0
             t_ss(i,j)=0.D0
           enddo
           enddo
         return
      endif
      call DerDerInvariIJJ(sig,pijkl,wijkl,n)
      call DerInvariIJJ(sig,I_s,J2_s,J3_s,n)
      call Invari_t(sig,n,t)
      tolt=1.D-6
      t   =3.D0*t
      if (t.lt.tolt) t=tolt
      if (t.gt.(4.D0*atan(1.D0)-tolt)) t=4.D0*atan(1.D0)-tolt      
      cst=dcos(t)
      snt=dsin(t)
      aux0=3.D0/(2.D0*q)
      aux1=-9.D0/(4.D0*q**3)
      aux2=3.D0/(2.D0*q*q)*cst/snt
      aux3=-9.D0/(2.D0*q**3)/snt
      aux4=-9.D0/(2.D0*q**4)*cst/snt-27.D0/(4.D0*q**4)*cst/snt**3
      aux5=81.D0/(4.D0*q**5)/snt**3
      aux6=-243.D0/(4.D0*q**6)*cst/snt**3
      do i=1,n
        do j=1,n
           q_ss(i,j)=aux0*pijkl(i,j)+aux1*J2_s(i)*J2_s(j)
           t_ss(i,j)=aux2*pijkl(i,j)+aux3*wijkl(i,j)+
     .               aux4*J2_s(i)*J2_s(j)+aux6*J3_s(i)*J3_s(j)+
     .               aux5*(J2_s(i)*J3_s(j)+J3_s(i)*J2_s(j))
        enddo
      enddo
      return
      end