diff --git a/.environment.yaml b/.environment.yaml
deleted file mode 100644
index c20b1b74..00000000
--- a/.environment.yaml
+++ /dev/null
@@ -1,19 +0,0 @@
-# conda env create -f environment.yml -n ...
-
-channels:
-    - conda-forge
-
-dependencies:
-    - pip<=20.2
-    - python=3.8
-    - h5py
-    - rdkit
-    - pandas
-    - numpy
-    - scipy
-
-    - pip:
-        - data-CAT@git+https://github.com/nlesc-nano/data-CAT@master
-        - nano-CAT@git+https://github.com/nlesc-nano/nano-CAT@master
-        - plams@git+https://github.com/SCM-NV/PLAMS@a5696ce62c09153a9fa67b2b03a750913e1d0924
-        - qmflows@git+https://github.com/SCM-NV/qmflows@master
diff --git a/.readthedocs.yml b/.readthedocs.yml
index daeb1fe4..4b70f816 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -12,11 +12,10 @@ sphinx:
 # Optionally build your docs in additional formats such as PDF
 formats: all
 
-conda:
-    environment: .environment.yaml
-
 # Optionally set the version of Python and requirements required to build your docs
 python:
     install:
         - method: pip
           path: .
+          extra_requirements:
+            - doc
diff --git a/docs/conf.py b/docs/conf.py
index 893e9d56..f8bb4f72 100755
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -29,11 +29,6 @@
 needs_sphinx = '2.4'
 
 
-# Output is processed with HTML4 writer.
-# Default is False.
-html4_writer = True
-
-
 # Add any Sphinx extension module names here, as strings.
 # They can be extensions coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = [
@@ -258,6 +253,11 @@
 # Defaults to False.
 napoleon_use_admonition_for_references = True
 
+# This value contains a list of modules to be mocked up.
+# This is useful when some external dependencies are not met at build time and break the building
+# process. You may only specify the root package of the dependencies themselves and
+# omit the sub-modules:
+autodoc_mock_imports = ["rdkit"]
 
 # A string of reStructuredText that will be included at the end of every source file that is read.
 # This is a possible place to add substitutions that should be available in every file (another being rst_prolog).