diff --git a/cmake/Modules/Packages/ML-PACE.cmake b/cmake/Modules/Packages/ML-PACE.cmake
index ccc7423355..998ef22191 100644
--- a/cmake/Modules/Packages/ML-PACE.cmake
+++ b/cmake/Modules/Packages/ML-PACE.cmake
@@ -1,6 +1,6 @@
 
-set(PACELIB_URL "https://github.com/ICAMS/lammps-user-pace/archive/refs/tags/v.2021.4.9.tar.gz" CACHE STRING "URL for PACE evaluator library sources")
-set(PACELIB_MD5 "4db54962fbd6adcf8c18d46e1798ceb5" CACHE STRING "MD5 checksum of PACE evaluator library tarball")
+set(PACELIB_URL "https://github.com/ICAMS/lammps-user-pace/archive/refs/tags/v.2021.9.28.tar.gz" CACHE STRING "URL for PACE evaluator library sources")
+set(PACELIB_MD5 "f98363bb98adc7295ea63974738c2a1b" CACHE STRING "MD5 checksum of PACE evaluator library tarball")
 mark_as_advanced(PACELIB_URL)
 mark_as_advanced(PACELIB_MD5)
 
@@ -14,12 +14,18 @@ execute_process(
   WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
 )
 
-file(GLOB PACE_EVALUATOR_INCLUDE_DIR ${CMAKE_BINARY_DIR}/lammps-user-pace-*/USER-PACE)
-file(GLOB PACE_EVALUATOR_SOURCES ${CMAKE_BINARY_DIR}/lammps-user-pace-*/USER-PACE/*.cpp)
+file(GLOB lib-pace ${CMAKE_BINARY_DIR}/lammps-user-pace-*)
+add_subdirectory(${lib-pace}/yaml-cpp build-yaml-cpp)
+set(YAML_CPP_INCLUDE_DIR ${lib-pace}/yaml-cpp/include)
+
+file(GLOB PACE_EVALUATOR_INCLUDE_DIR ${lib-pace}/ML-PACE)
+file(GLOB PACE_EVALUATOR_SOURCES ${lib-pace}/ML-PACE/*.cpp)
 list(FILTER PACE_EVALUATOR_SOURCES EXCLUDE REGEX pair_pace.cpp)
 
 add_library(pace STATIC ${PACE_EVALUATOR_SOURCES})
 set_target_properties(pace PROPERTIES CXX_EXTENSIONS ON OUTPUT_NAME lammps_pace${LAMMPS_MACHINE})
-target_include_directories(pace PUBLIC ${PACE_EVALUATOR_INCLUDE_DIR})
-target_link_libraries(lammps PRIVATE pace)
+target_include_directories(pace PUBLIC ${PACE_EVALUATOR_INCLUDE_DIR} ${YAML_CPP_INCLUDE_DIR})
+
+target_link_libraries(lammps PRIVATE pace)
+target_link_libraries(lammps PRIVATE yaml-cpp)
 
diff --git a/lib/pace/Install.py b/lib/pace/Install.py
index e90ae8c312..946c29676a 100644
--- a/lib/pace/Install.py
+++ b/lib/pace/Install.py
@@ -15,12 +15,13 @@ from install_helpers import fullpath, geturl, checkmd5sum
 # settings
 
 thisdir = fullpath('.')
-version = 'v.2021.4.9'
+version = 'v.2021.9.28'
 
 # known checksums for different PACE versions. used to validate the download.
 checksums = { \
         'v.2021.2.3.upd2' : '8fd1162724d349b930e474927197f20d',
         'v.2021.4.9'      : '4db54962fbd6adcf8c18d46e1798ceb5',
+        'v.2021.9.28'     : 'f98363bb98adc7295ea63974738c2a1b',
         }
 
 
diff --git a/lib/pace/Makefile b/lib/pace/Makefile
index c2e1892ddd..81f7c9db95 100644
--- a/lib/pace/Makefile
+++ b/lib/pace/Makefile
@@ -2,8 +2,11 @@ SHELL = /bin/sh
 
 # ------ FILES ------
 
-SRC_FILES = $(wildcard src/USER-PACE/*.cpp)
-SRC = $(filter-out src/USER-PACE/pair_pace.cpp, $(SRC_FILES))
+YAML_CPP_PATH = src/yaml-cpp
+YAML_CPP_INC = $(YAML_CPP_PATH)/include
+
+SRC_FILES = $(wildcard src/ML-PACE/*.cpp)
+SRC = $(filter-out src/ML-PACE/pair_pace.cpp, $(SRC_FILES))
 
 # ------ DEFINITIONS ------
 
@@ -12,7 +15,7 @@ OBJ =   $(SRC:.cpp=.o)
 
 
 # ------ SETTINGS ------
-CXXFLAGS = -O3 -fPIC -Isrc/USER-PACE
+CXXFLAGS = -O3 -fPIC -Isrc/ML-PACE -I$(YAML_CPP_INC)
 
 ARCHIVE =	ar
 ARCHFLAG =	-rc
@@ -21,9 +24,13 @@ SYSLIB =
 
 # ------ MAKE PROCEDURE ------
 
-lib: $(OBJ)
+lib: $(OBJ) lib-yaml-cpp
 	$(ARCHIVE) $(ARFLAGS) $(LIB) $(OBJ)
 
+
+lib-yaml-cpp:
+	cd $(YAML_CPP_PATH) && $(MAKE) lib
+
 # ------ COMPILE RULES ------
 
 %.o: %.cpp
@@ -32,6 +39,9 @@ lib: $(OBJ)
 # ------ CLEAN ------
 clean-all:
 	-rm -f *~ $(OBJ) $(LIB)
+	cd $(YAML_CPP_PATH) && $(MAKE) clean-all
 
 clean-build:
 	-rm -f *~ $(OBJ)
+	cd $(YAML_CPP_PATH) && $(MAKE) clean-build
+
diff --git a/lib/pace/Makefile.lammps b/lib/pace/Makefile.lammps
index 17820716df..f4cbeb8ffd 100644
--- a/lib/pace/Makefile.lammps
+++ b/lib/pace/Makefile.lammps
@@ -1,3 +1,3 @@
-pace_SYSINC =-I../../lib/pace/src/USER-PACE
-pace_SYSLIB = -L../../lib/pace/ -lpace
+pace_SYSINC =-I../../lib/pace/src/ML-PACE -I../../lib/pace/src/yaml-cpp/include
+pace_SYSLIB = -L../../lib/pace/ -lpace -L../../lib/pace/src/yaml-cpp/ -lyaml-cpp
 pace_SYSPATH =
diff --git a/src/ML-PACE/pair_pace.cpp b/src/ML-PACE/pair_pace.cpp
index f0d6547083..4a8f7d9512 100644
--- a/src/ML-PACE/pair_pace.cpp
+++ b/src/ML-PACE/pair_pace.cpp
@@ -296,10 +296,9 @@ void PairPACE::coeff(int narg, char **arg) {
 
   //load potential file
   delete aceimpl->basis_set;
-  aceimpl->basis_set = new ACECTildeBasisSet();
-  if (comm->me == 0)
-    utils::logmesg(lmp,"Loading {}\n", potential_file_name);
-  aceimpl->basis_set->load(potential_file_name);
+    if (comm->me == 0)
+        utils::logmesg(lmp,"Loading {}\n", potential_file_name);
+  aceimpl->basis_set = new ACECTildeBasisSet(potential_file_name);
 
   if (comm->me == 0) {
     utils::logmesg(lmp,"Total number of basis functions\n");