diff --git a/benchmark.jl b/benchmark.jl
index c7525ad..fffef78 100644
--- a/benchmark.jl
+++ b/benchmark.jl
@@ -27,11 +27,10 @@ end
 
 N=10
 n_image=1
-μ=0.5
 
 for L in 5.0:14.0
     println("Constructing H operator...")
-    s=system{T}(3,3,N,L,μ)
+    s=system{T}(3,3,N,L)
     @time H=Hamiltonian{T}(s,V_test,0,n_image,mode)
     println("Applying H 1000 times...")
     if GPU_mode
diff --git a/common.jl b/common.jl
index c496a0a..aae050d 100644
--- a/common.jl
+++ b/common.jl
@@ -8,7 +8,7 @@ struct system{T}
     L::T
     μ::T
 
-    system{T}(d::Int, n::Int, N::Int, L::Real, μ::Real) where {T<:Float} = new{T}(d, n, N, convert(T, L), convert(T, μ))
+    system{T}(d::Int, n::Int, N::Int, L::Real, μ::Real=0.5) where {T<:Float} = new{T}(d, n, N, convert(T, L), convert(T, μ))
 end
 
 norm_square(x::Array{Int})::Int = sum(x .* x)
diff --git a/example.ipynb b/example.ipynb
index 17e9f75..d46f387 100644
--- a/example.ipynb
+++ b/example.ipynb
@@ -26,10 +26,9 @@
     "N = 6\n",
     "L = 12\n",
     "ϕ = 0.0\n",
-    "μ = 0.5\n",
     "n_imag = 1\n",
     "\n",
-    "s = system{T}(d, n, N, L, μ)\n",
+    "s = system{T}(d, n, N, L)\n",
     "H = Hamiltonian{T}(s, V_gauss, ϕ, n_imag, mode)\n",
     "@time evals, evecs, info = eig(H, 5)\n",
     "print(info.numops, \" operations : \")\n",
@@ -52,10 +51,9 @@
     "N = 32\n",
     "L = 16\n",
     "ϕ = 0.5\n",
-    "μ = 0.5\n",
     "n_imag = 0\n",
     "\n",
-    "s = system{T}(d, n, N, L, μ)\n",
+    "s = system{T}(d, n, N, L)\n",
     "H = Hamiltonian{T}(s, V_gauss, ϕ, n_imag, mode)\n",
     "@time evals, evecs, info = eig(H, 20)\n",
     "print(info.numops, \" operations : \")\n",
diff --git a/testing.ipynb b/testing.ipynb
index b59c088..11a2c5c 100644
--- a/testing.ipynb
+++ b/testing.ipynb
@@ -24,7 +24,7 @@
     "        n_image=0\n",
     "        for L::T in 5.0:9.0\n",
     "            print(\"L=$L\")\n",
-    "            s=system{T}(3,n,N,L,0.5)\n",
+    "            s=system{T}(3,n,N,L)\n",
     "            H=Hamiltonian{T}(s,V_test,0.0,n_image,mode)\n",
     "            evals,_,_ = eig(H,5)\n",
     "            println(real.(evals))\n",