diff --git a/deeprank/generate/DataGenerator.py b/deeprank/generate/DataGenerator.py
index ac152c25..e6fd8c31 100644
--- a/deeprank/generate/DataGenerator.py
+++ b/deeprank/generate/DataGenerator.py
@@ -1022,7 +1022,6 @@ def precompute_grid(self,
 #
 # ====================================================================================
 
-
     def map_features(self, grid_info={},
                      cuda=False, gpu_block=None,
                      cuda_kernel='/kernel_map.c',
@@ -1102,7 +1101,8 @@ def map_features(self, grid_info={},
 
         # by default we do not map atomic densities
         if 'atomic_densities' not in grid_info:
-            grid_info['atomic_densities'] = None
+            grid_info['atomic_densities'] = {
+                'C': 1.7, 'N': 1.55, 'O': 1.52, 'S': 1.8}
 
         # fills in the features mode if somes are missing : default = IND
         modes = ['atomic_densities_mode', 'feature_mode']
@@ -1267,7 +1267,6 @@ def remove(self, feature=True, pdb=True, points=True, grid=False):
 #
 # ====================================================================================
 
-
     def _tune_cuda_kernel(self, grid_info, cuda_kernel='kernel_map.c', func='gaussian'):  # pragma: no cover
         """Tune the CUDA kernel using the kernel tuner
         http://benvanwerkhoven.github.io/kernel_tuner/
@@ -1343,7 +1342,6 @@ def _tune_cuda_kernel(self, grid_info, cuda_kernel='kernel_map.c', func='gaussia
 #
 # ====================================================================================
 
-
     def _test_cuda(self, grid_info, gpu_block=8, cuda_kernel='kernel_map.c', func='gaussian'):  # pragma: no cover
         """Test the CUDA kernel.
 
@@ -1478,7 +1476,6 @@ def _tunable_kernel(kernel):  # pragma: no cover
 #
 # ===================================================================================
 
-
     def _filter_cplx(self):
         """Filter the name of the complexes."""
 
@@ -1561,7 +1558,6 @@ def _compute_targets(targ_list, pdb_data, targrp):
 #
 # ====================================================================================
 
-
     def _add_pdb(self, molgrp, pdbfile, name):
         """Add a pdb to a molgrp.