diff --git a/doc/src/Commands_all.txt b/doc/src/Commands_all.txt
index d0d7657c07..ecd21e42e7 100644
--- a/doc/src/Commands_all.txt
+++ b/doc/src/Commands_all.txt
@@ -124,6 +124,7 @@ An alphabetic list of all general LAMMPS commands.
 "thermo"_thermo.html,
 "thermo_modify"_thermo_modify.html,
 "thermo_style"_thermo_style.html,
+"third_order"_third_order.html,
 "timer"_timer.html,
 "timestep"_timestep.html,
 "uncompute"_uncompute.html,
diff --git a/doc/src/Packages_details.txt b/doc/src/Packages_details.txt
index eead133add..fc30c045cf 100644
--- a/doc/src/Packages_details.txt
+++ b/doc/src/Packages_details.txt
@@ -1746,11 +1746,12 @@ USER-PHONON package :link(PKG-USER-PHONON),h4
 A "fix phonon"_fix_phonon.html command that calculates dynamical
 matrices, which can then be used to compute phonon dispersion
 relations, directly from molecular dynamics simulations.
-And a "dynamical_matrix" command to compute the dynamical matrix
-from finite differences.
+And a "dynamical_matrix"_dynamical_matrix.html as well as a
+"third_order"_third_order.html command to compute the dynamical matrix
+and third order tensor from finite differences.
 
 [Authors:] Ling-Ti Kong (Shanghai Jiao Tong University) for "fix phonon"
-and Charlie Sievers (UC Davis) for "dynamical_matrix"
+and Charlie Sievers (UC Davis) for "dynamical_matrix" and "third_order"
 
 
 [Supporting info:]
@@ -1759,6 +1760,7 @@ src/USER-PHONON: filenames -> commands
 src/USER-PHONON/README
 "fix phonon"_fix_phonon.html
 "dynamical_matrix"_dynamical_matrix.html
+"third_order"_third_order.html
 examples/USER/phonon :ul
 
 :line
diff --git a/doc/src/commands_list.txt b/doc/src/commands_list.txt
index a5c9b568ed..714aedefed 100644
--- a/doc/src/commands_list.txt
+++ b/doc/src/commands_list.txt
@@ -108,6 +108,7 @@ Commands :h1
    thermo
    thermo_modify
    thermo_style
+   third_order
    timer
    timestep
    uncompute
diff --git a/doc/src/lammps.book b/doc/src/lammps.book
index 9868c8f299..eec7520fdc 100644
--- a/doc/src/lammps.book
+++ b/doc/src/lammps.book
@@ -217,6 +217,7 @@ temper_npt.html
 thermo.html
 thermo_modify.html
 thermo_style.html
+third_order.html
 timer.html
 timestep.html
 uncompute.html
diff --git a/src/USER-PHONON/README b/src/USER-PHONON/README
index b554eacd5e..d5ed666c0c 100644
--- a/src/USER-PHONON/README
+++ b/src/USER-PHONON/README
@@ -3,11 +3,11 @@ matrices from finite temperature MD simulations, which can then be
 used to compute phonon dispersion relations, directly from molecular
 dynamics simulations.
 
-It also contains a command to compute the dynamical matrix at
-pre-optimized positions through finite differences.
+It also contains commands to compute the dynamical matrix and third
+order tensor at pre-optimized positions through finite differences.
 
 See the doc page for the fix phonon command or the dynamical_matrix
-command for detailed usage instructions.
+or third_order commands for detailed usage instructions.
 
 Use of this package requires building LAMMPS with FFT suppport, as
 described in doc/Section_start.html.