diff --git a/doc/src/atc_hardy_on_the_fly.rst b/doc/src/atc_hardy_on_the_fly.rst
new file mode 100644
index 0000000000..0aa186f219
--- /dev/null
+++ b/doc/src/atc_hardy_on_the_fly.rst
@@ -0,0 +1,54 @@
+.. index:: fix_modify AtC on_the_fly
+
+fix_modify AtC on_the_fly command
+=================================
+
+Syntax
+""""""
+
+.. parsed-literal::
+
+   fix_modify <AtC fixID> on_the_fly on_the_fly <bond|kernel> <on|off>
+
+* AtC fixID = ID of :doc:`fix atc <fix_atc>` instance
+* on_the_fly = name of the AtC sub-command
+* *bond* or *kernel* = specifies on-the-fly calculation of *bond* or *kernel* matrix elements
+* *on* or *off* = activate or discontinue on-the-fly mode
+
+Examples
+""""""""
+
+.. code-block:: LAMMPS
+
+   fix_modify AtC on_the_fly bond on
+   fix_modify AtC on_the_fly kernel
+   fix_modify AtC on_the_fly kernel off
+
+Description
+"""""""""""
+
+Overrides normal mode of pre-calculating and storing bond pair-to-node a
+nd kernel atom-to-node matrices. If activated, it will calculate elements
+of these matrices during repeated calls of field computations
+(i.e. "on-the-fly") and not store them for future use.  The *on* flag is
+optional - if omitted, on_the_fly will be activated for the specified
+matrix.  Can be deactivated using the *off* flag.
+
+Restrictions
+""""""""""""
+
+Must be used with :doc:`fix atc hardy <fix_atc>`.
+
+Related AtC commands
+""""""""""""""""""""
+
+- :ref:`fix_modify AtC command overview <atc_fix_modify>`
+
+Default
+"""""""
+
+By default, on-the-fly calculation is not active (i.e. off). However,
+THE code does a memory allocation check to determine if it can store all
+needed bond and kernel matrix elements. If this allocation fails,
+on-the-fly will be activated.
+
diff --git a/doc/src/fix_atc.rst b/doc/src/fix_atc.rst
index 19e4cffbbb..902c336706 100644
--- a/doc/src/fix_atc.rst
+++ b/doc/src/fix_atc.rst
@@ -211,7 +211,7 @@ conditions.
 * :doc:`fix_modify AtC gradients <atc_hardy_gradients>`
 * :doc:`fix_modify AtC rates <atc_hardy_rates>`
 * :doc:`fix_modify AtC computes <atc_hardy_computes>`
-* `fix_modify AtC on_the_fly <USER/atc/man_hardy_on_the_fly.html>`_
+* :doc:`fix_modify AtC on_the_fly <atc_hardy_on_the_fly>`
 * `fix_modify AtC pair_interactions/bond_interactions <USER/atc/man_pair_interactions.html>`_
 * `fix_modify AtC sample_frequency <USER/atc/man_sample_frequency.html>`_
 * `fix_modify AtC set <USER/atc/man_set.html>`_