diff --git a/src/py4vasp/_raw/data.py b/src/py4vasp/_raw/data.py
index 60f80833..d0a70e45 100644
--- a/src/py4vasp/_raw/data.py
+++ b/src/py4vasp/_raw/data.py
@@ -533,7 +533,7 @@ class ElectronPhononSelfEnergy(schema.Sequence):
     eigenvalues: VaspData
     debye_waller: VaspData
     fan: VaspData
-
+    bks_idx: VaspData
 
 @dataclasses.dataclass
 class ElectronPhononTransport(schema.Sequence):
diff --git a/src/py4vasp/_raw/definition.py b/src/py4vasp/_raw/definition.py
index 717e393d..7e494fbf 100644
--- a/src/py4vasp/_raw/definition.py
+++ b/src/py4vasp/_raw/definition.py
@@ -528,15 +528,16 @@ def selections(quantity):
 schema.add(
     raw.ElectronPhononSelfEnergy,
     required=raw.Version(6, 5),
-    size=f"{group}/self_energy_meta/id_size",
+    size=f"{group}/self_energy_meta/ncalculators",
     eigenvalues=f"{group}/eigenvalues/eigenvalues",
     debye_waller=f"{group}/self_energy_{{}}/selfen_dw",
+    bks_idx=f"{group}/self_energy_{{}}/bks_idx",
     fan=f"{group}/self_energy_{{}}/selfen_fan",
 )
 schema.add(
     raw.ElectronPhononTransport,
     required=raw.Version(6, 5),
-    size=f"{group}/transport_meta/id_size",
+    size=f"{group}/transport_meta/ncalculators",
     mobility=f"{group}/transport_{{}}/mobility",
     transport_function=f"{group}/transport_{{}}/transport_function",
 )
diff --git a/src/py4vasp/calculation/__init__.py b/src/py4vasp/calculation/__init__.py
index 29500579..07808220 100644
--- a/src/py4vasp/calculation/__init__.py
+++ b/src/py4vasp/calculation/__init__.py
@@ -80,7 +80,7 @@ class provides a more flexible interface with which you can determine the source
     "workfunction",
 )
 _nested = {
-    "electron_phonon": ("self_energy",),
+    "electron_phonon": ("self_energy","transport",),
 }
 _private = ("dispersion",)
 __all__ = _quantities + tuple(_nested) + _input_files
diff --git a/src/py4vasp/calculation/_electron_phonon_self_energy.py b/src/py4vasp/calculation/_electron_phonon_self_energy.py
index be1b02f6..60dc7641 100644
--- a/src/py4vasp/calculation/_electron_phonon_self_energy.py
+++ b/src/py4vasp/calculation/_electron_phonon_self_energy.py
@@ -18,6 +18,33 @@ def to_dict(self):
             "fan": self._read_slice_of_data("fan"),
         }
 
+    def __len__(self):
+        return self._raw_data.size
+
     def _read_slice_of_data(self, name):
         slice_of_data = getattr(self._raw_data, name)[self._steps]
         return [data[:] for data in slice_of_data]
+
+    def select(self, selection):
+        tree = select.Tree.from_string(selection)
+        for selection in tree.selections():
+            print(selection)
+
+    def get_fan(self,arg):
+        iband,ikpt,isp,*more = arg
+        st = SparseTensor(self._raw_data.bks_idx,
+                          self._raw_data.fan)
+        return st(iband,ikpt,isp)
+
+class SparseTensor():
+    def __init__(self,bks_idx,tensor):
+        self.bks_idx = bks_idx
+        self.tensor = tensor
+
+    def _get_ibks(self,iband,ikpt,isp):
+        return self.bks_idx[iband,ikpt,isp]
+
+    def __getitem__(self,arg):
+        iband,ikpt,isp,*more = arg
+        ibks = self._get_ibks(iband,ikpt,isp)
+        return self.tensor[ibks,more]
diff --git a/src/py4vasp/calculation/_electron_phonon_transport.py b/src/py4vasp/calculation/_electron_phonon_transport.py
new file mode 100644
index 00000000..4fe0077f
--- /dev/null
+++ b/src/py4vasp/calculation/_electron_phonon_transport.py
@@ -0,0 +1,25 @@
+# Copyright © VASP Software GmbH,
+# Licensed under the Apache License 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
+from py4vasp.calculation import _base, _slice
+
+
+class ElectronPhononTransport(_slice.Mixin, _base.Refinery):
+    "Placeholder for electron phonon transport"
+
+    @_base.data_access
+    def __str__(self):
+        return "electron phonon transport"
+
+    @_base.data_access
+    def to_dict(self):
+        return {
+            "transport_function": self._read_slice_of_data("transport_function"),
+            "mobility": self._read_slice_of_data("mobility"),
+        }
+
+    def __len__(self):
+        return self._raw_data.size
+
+    def _read_slice_of_data(self, name):
+        slice_of_data = getattr(self._raw_data, name)[self._steps]
+        return [data[:] for data in slice_of_data]