diff --git a/ho_basis.jl b/ho_basis.jl
new file mode 100644
index 0000000..5746fc6
--- /dev/null
+++ b/ho_basis.jl
@@ -0,0 +1,24 @@
+# Gaussian potentials in HO space
+gl(R, l, k) = throw("unimplemented")
+
+function get_sp_basis(max_N)
+    ls = Int[]
+    ks = Int[]
+
+    # Heyde p67
+    for N in max_N:-1:0
+        for l in N:-2:0
+            k = (N - l) / 2
+            push!(ls, l)
+            push!(ks, k)
+        end
+    end
+
+    return (ls, ks)
+end
+
+get_V_matrix(V_lk, ls, ks) = throw("unimplemented")
+
+get_T_matrix(ls, ks) = throw("unimplemented")
+
+get_H_matrix(V_ls, ls, ks) = get_T_matrix(ls, ks) + get_V_matrix(V_lk, ls, ks)