     // determine which particle this thread works on
     int group_idx = blockIdx.x * blockDim.x + threadIdx.x;
 
-    // propagate velocity from t to t+1/2*deltaT and position from t to t+deltaT
-    // according to the Nose-Hoover barostat
     if (group_idx < group_size)
         {
         unsigned int idx = d_group_members[group_idx];

        v = v*exp_v_fac_thermo;

        // write out the results
        vel.x = v.x;
        vel.y = v.y;
        vel.z = v.z;

        d_vel[idx] = vel;

        }
    }

        v = v*exp_v_fac_2 + Scalar(1.0/2.0)*deltaT*accel*exp_v_fac*sinhx_fac_v;
        r = r*exp_r_fac_2 + v*exp_r_fac*sinhx_fac_r*deltaT;

        // write out the results
        d_pos[idx] = make_scalar4(r.x,r.y,r.z,pos.w);
        d_vel[idx] = make_scalar4(v.x,v.y,v.z,vel.w);
        }
    }

