Fixed a missing file issue

examples/data/xyz/acrolein.xyz

@@ -0,0 +1,10 @@
+8
+
+O  -1.808864  -0.137998  0.000000
+C  1.769114  0.136549  0.000000
+C  0.588145  -0.434423  0.000000
+C  -0.695203  0.361447  0.000000
+H  -0.548852  1.455362  0.000000
+H  0.477859  -1.512556  0.000000
+H  2.688665  -0.434186  0.000000
+H  1.880903  1.213924  0.000000 

examples/huckel.py

@@ -1,12 +1,13 @@
 from tcintegral import basis_set, MolecularOrbital
 from scm import plams
-
+import numpy as np 
+from tcviewer import Screen, materials
 
 # get a basis set from basis_sets
 bs = basis_set.STO2G
 
 # read a molecule to use
-mol = plams.Molecule('/Users/yumanhordijk/Desktop/acrolein.xyz')
+mol = plams.Molecule('../examples/data/xyz/acrolein.xyz')
 mol.guess_bonds()
 
 # get atomic orbitals for this molecule