diff --git a/lib/objects.py b/lib/objects.py
index 997f5cf..7179baf 100755
--- a/lib/objects.py
+++ b/lib/objects.py
@@ -186,6 +186,7 @@ class System(Body):
     def eccCOM(self): #exentricity of two body sub system
         if len(self.bodylist) == 2 :
             ecc = (2.*self.ECOM*(np.linalg.norm(self.LCOM)**2))/(Ga**2*self.M**2*self.mu**3) + 1.
+
         else :
             ecc = np.nan
         return ecc
@@ -215,13 +216,15 @@ class System(Body):
         return sma
 
     @property
-    def phi(self): #return angle in degree between plans formed by body1 and body2 (perurbator) trajectories
+    def phi(self): #return angle in degree between plans formed by perturbator plan and reference plan
         if len(self.bodylist) == 3 :
             body1 = self.bodylist[0]
             body2 = self.bodylist[2]
-            n1 = np.cross(body1.q, body1.v)
-            n2 = np.cross(body2.q, body2.v)
+            n1 = np.cross(body1.q-self.COM, body1.v-self.COMV)
+            n2 = np.cross(body2.q-self.COM, body2.v-self.COMV)
+            n1 = np.array([0., 0., 1.], dtype=np.longdouble)
             phi = np.arccos(np.dot(n1, n2) / (np.linalg.norm(n1) * np.linalg.norm(n2)))*180./np.pi
         else :
             phi = np.nan
-        return phi
\ No newline at end of file
+        return phi
+
diff --git a/main.py b/main.py
index 92d380c..6ad0d42 100755
--- a/main.py
+++ b/main.py
@@ -12,7 +12,7 @@ from lib.units import *
 def main():
     #initialisation
     m = np.array([1., 1., 1e-1],dtype=np.longdouble)*Ms#/Ms  # Masses in Solar mass
-    a = np.array([1., 1., 5.5],dtype=np.longdouble)*au#/au   # Semi-major axis in astronomical units
+    a = np.array([.75, .75, 5.],dtype=np.longdouble)*au#/au   # Semi-major axis in astronomical units
     e = np.array([0., 0., 0.25],dtype=np.longdouble)   # Eccentricity
     psi = np.array([0., 0., 80.],dtype=np.longdouble)*np.pi/180.    # Inclination of the orbital plane in degrees
 
@@ -27,7 +27,7 @@ def main():
     v = np.array([v1, v2, v3],dtype=np.longdouble)
 
     #integration parameters
-    duration, step = 5000*yr, np.longdouble(1./2.*86400.) #integration time and step in seconds
+    duration, step = 1000*yr, np.longdouble(1./2.*86400.) #integration time and step in seconds
     integrator = "leapfrog"
     n_bodies = 3
     display = False
diff --git a/plots/3bodies_leapfrog_E.png b/plots/3bodies_leapfrog_E.png
index 7902e93..5555451 100644
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diff --git a/plots/3bodies_leapfrog_L.png b/plots/3bodies_leapfrog_L.png
index a8579ef..f3decfc 100644
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diff --git a/plots/3bodies_leapfrog_a_e.png b/plots/3bodies_leapfrog_a_e.png
index 68f8f21..b118a38 100644
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diff --git a/plots/3bodies_leapfrog_dEm.png b/plots/3bodies_leapfrog_dEm.png
index 0c24328..b0b3583 100644
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diff --git a/plots/3bodies_leapfrog_dL2.png b/plots/3bodies_leapfrog_dL2.png
index 4f9e3eb..0cfaed5 100644
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diff --git a/plots/3bodies_leapfrog_phi.png b/plots/3bodies_leapfrog_phi.png
index 77f423b..249a0e5 100644
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