diff --git a/code/m_chemistry.f90 b/code/m_chemistry.f90
index 3d72f64..fc71a4a 100644
--- a/code/m_chemistry.f90
+++ b/code/m_chemistry.f90
@@ -4,8 +4,21 @@ use m_parameters
 
 implicit none
 
+real, private :: coef(10)
+real, private :: lambda_onestep
+
 contains
 
+subroutine init_chemistry
+    if ( reaction_type == "onestep" ) then
+        lambda_onestep = pre * exp ( - beta / hrp )
+    else if ( reaction_type == "twostep" ) then
+    else
+        stop
+    end if
+
+end subroutine init_chemistry
+
 real function rate_1step (yr, theta)
 
     real, intent(in)  :: yr
diff --git a/code/m_parameters.f90 b/code/m_parameters.f90
index 0367666..0c1a243 100644
--- a/code/m_parameters.f90
+++ b/code/m_parameters.f90
@@ -16,7 +16,7 @@ module m_parameters
 
      real :: pre,ac,bc,c_cut,c_ref
 
-     real :: lambda1, lambda2, beta1, hrp
+     real :: lambda1, lambda2, beta1, hrp, beta
 
      integer :: syp,eyp,twod
 
@@ -44,10 +44,13 @@ module m_parameters
 
      CHARACTER(100) :: itape_name
 
+     CHARACTER(100) :: reaction_type
+
 contains
 
      SUBROUTINE SET_CHEMISTRY
 
+       reaction_type = "twostep"
        lambda1 = 100000.
        lambda2 = lambda1 * 63.6
        beta1 = 9.1
@@ -60,6 +63,8 @@ contains
        INTEGER :: itape=300,otape=301
        INTEGER :: i
 
+       CALL SET_CHEMISTRY
+
        IF (read_stdin) THEN
          itape=5
        ELSE
diff --git a/code/ysolve.f90 b/code/ysolve.f90
index 1a784d1..ec7b0ae 100644
--- a/code/ysolve.f90
+++ b/code/ysolve.f90
@@ -79,8 +79,6 @@
       INTEGER :: i,j,k,savenum
       REAL :: pflame,pflold,delf=0.
 
-      CALL ludcmp(nx,100,100,1,0,0)
-
       CALL SET_IC
 
       t_now=0.
@@ -342,6 +340,8 @@
        ALLOCATE(duxt(nx),STAT=ierr)    ; duxt=0.
        ALLOCATE(dm(nx),STAT=ierr)      ; dm=diff
 
+       CALL ludcmp(nx,100,100,1,0,0)
+
      END SUBROUTINE init_solver
 
      SUBROUTINE finalize_solver