c-----------------------------------------------------------------
      subroutine tnp_respa_step1
c Applying Nose-Poincare algorithm - step 1 to vel for RESPA
c J.Comput.Phys. 151 114 (1999) S.D.Bond B.J.Leimkuhler B.B.Laird
c
c d_t is not updated here, it is destroyed
c
      implicit real*8 (a-h,o-z)
      include 'DIMENSIONS'
      include 'COMMON.CONTROL'
      include 'COMMON.VAR'
      include 'COMMON.MD'
      include 'COMMON.CHAIN'
      include 'COMMON.DERIV'
      include 'COMMON.GEO'
      include 'COMMON.LOCAL'
      include 'COMMON.INTERACT'
      include 'COMMON.IOUNITS'
      include 'COMMON.NAMES'
      double precision C_np,d_time_s,tmp,d_time_ss
      double precision energia(0:n_ene)

      d_time_s=d_time*0.5*s_np        

      do j=1,3
        d_t_old(j,0)=d_t_old(j,0)+d_a(j,0)*d_time_s
      enddo
      do i=nnt,nct-1	
        do j=1,3    
          d_t_old(j,i)=d_t_old(j,i)+d_a(j,i)*d_time_s
        enddo
      enddo
      do i=nnt,nct
        if (itype(i).ne.10) then
          inres=i+nres
          do j=1,3    
           d_t_old(j,inres)=d_t_old(j,inres)+d_a(j,inres)*d_time_s
          enddo
        endif      
      enddo 


c      C_np=0.5*d_time*(dimen*Rb*t_bath*(1.0+log(s_np))-EK+potE-H0)
c     &                     -pi_np
c
c      pistar=-2.0*C_np/(1.0+sqrt(1.0-C_np*d_time/Q_np))
c      tmp=0.5*d_time*pistar/Q_np
c      s12_np=s_np*(1.0+tmp)/(1.0-tmp)
c      write(iout,*) 'tnp_respa_step1',s_np,s12_np,EK,potE,C_np,pistar,tmp

ct1      pi_np=pistar
c      sold_np=s_np
c      s_np=s12_np

c-------------------------------------
c test of reviewer's comment
       pi_np=pi_np-0.5*d_time*(E_long+Csplit-H0)
cr       print '(a,3f)','1 pi_np,s_np',pi_np,s_np,E_long
c-------------------------------------

      return
      end