diff --git a/easybuild/easyconfigs/p/PSI4/PSI4-1.6.1-foss-2021b.eb b/easybuild/easyconfigs/p/PSI4/PSI4-1.6.1-foss-2021b.eb
new file mode 100644
index 000000000000..4c8ebae75f93
--- /dev/null
+++ b/easybuild/easyconfigs/p/PSI4/PSI4-1.6.1-foss-2021b.eb
@@ -0,0 +1,97 @@
+# Using the foss toolchain, not downloading any packages as they are coming
+# from EasyBuild and thus can be tested which the download version does not do
+# Tests enabled, default is the continuous integration checks testset 
+# J. Sassmannshausen (Imperial College London/UK)
+
+easyblock = 'EB_PSI'
+
+name = 'PSI4'
+version = '1.6.1'
+
+homepage = 'http://www.psicode.org/'
+description = """PSI4 is an open-source suite of ab initio quantum chemistry programs designed for
+ efficient, high-accuracy simulations of a variety of molecular properties. We can routinely perform
+ computations with more than 2500 basis functions running serially or in parallel."""
+
+toolchain = {'name': 'foss', 'version': '2021b'}
+toolchainopts = {'usempi': True}
+
+github_account = 'psi4'
+source_urls = [GITHUB_LOWER_SOURCE]
+sources = ['v%(version)s.tar.gz']
+patches = [
+    'PSI4-%(version)s_fix_cmake_release.patch',
+    'psi4-pythonpath.patch',
+]
+checksums = [
+    'bdcb9f9a433b5cf8410c7bed006f81fce5b71649bdb1d5b5fac8c8f64829173c',  # v1.6.1.tar.gz
+    '819e40468c5159992a102868c2308079acacdad03d395fed7e98653c3e85cd42',  # PSI4-1.6.1_fix_cmake_release.patch
+    'e8eeb1413b733fd10a487997066195e2fe8de90a32fb77cb7d84a6e7c550b29b',  # psi4-pythonpath.patch
+]
+
+builddependencies = [
+    ('CMake', '3.22.1'),
+    ('Boost', '1.77.0'),
+    ('Eigen', '3.4.0'),
+    ('Ninja', '1.10.2'),
+    ('pytest', '7.1.3'),
+]
+
+dependencies = [
+    ('Python', '3.9.6'),
+    ('libxc', '5.1.6'),
+    #  PCMSolver version 1.3.0 fails Green spherical diffuse test.
+    #  See in more details: https://github.com/PCMSolver/pcmsolver/issues/159
+    # ('PCMSolver', '1.3.0'),
+    ('CheMPS2', '1.8.11'),
+    ('networkx', '2.6.3'),
+    ('deepdiff', '5.7.0'),
+    ('MPFR', '4.1.0'),
+    ('pydantic', '1.10.2'),
+    ('Pint', '0.19.2'),
+    ('py-cpuinfo', '8.0.0'),
+    ('qcengine', '0.24.1'),
+    ('libefp', '1.5.0', '-psi4'),
+    ('cppe', '0.3.1'),
+    ('pylibefp', '0.6.1', '-qcengine-0.24.1'),
+    ('dkh', '1.2', '-psi4'),
+    ('Libint2', '5-4-3-6-5-4_mm4f12ob2', '-lmax-5-psi4'),
+    ('libecpint', '1.0.7', '-psi4'),
+    ('gau2grid', '2.0.7', '-lmax-5-psi4'),
+    ('ambit', '733c529', '-psi4'),
+    ('gdma', '2.2.6'),
+    ('simint', '0.7', '-lmax-5-vec-avx-psi4'),
+    ('cppe', '0.3.1'),
+    # snsmp2 does not seem to work during the build but it is a runtime option
+    # so that needs to be loaded after PSI4 is build
+]
+
+configopts = '-DENABLE_MPI=ON -DENABLE_PLUGINS=ON -DENABLE_XHOST=OFF '
+# We are using FlexiBLAS:
+configopts += '-DBLAS_TYPE=FLEXIBLAS -DLAPACK_TYPE=FLEXIBLAS '
+# We use libxc etc from EasyBuild:
+configopts += '-DLibxc_DIR=${EBROOTLIBXC} -DENABLE_CheMPS2=ON -DENABLE_PCMSolver=OFF '
+#  Add packages, coming from EasyBuild and not downloaded
+# -DENABLE_simint=ON does not work with intel/2018, so have to make with GCCcore
+configopts += '-DENABLE_dkh=ON -DENABLE_gdma=ON -DENABLE_resp=ON -DENABLE_snsmp2=OFF -DENABLE_simint=ON '
+configopts += '-DENABLE_ambit=ON -DENABLE_cppe=ON -DENABLE_adcc=OFF -DENABLE_ecpint=ON -DENABLE_libefp=ON '
+configopts += '-Dlibefp_DIR=${EBROOTLIBEFP} -Dambit_DIR=${EBROOTAMBIT} '
+configopts += '-DENABLE_libint2=OFF '
+
+#  Install python module to the standard location instead of lib
+configopts += '-DPYMOD_INSTALL_LIBDIR=/python%(pyshortver)s/site-packages '
+
+# All important testing. The suggtested 'quick' runs 177 test, 'smoke' only 20
+# The full test would be 509
+# Short test of 20 test cases:
+# runtest = ' -L smoke'
+# Full test of 509 test cases
+# runtest = ' '
+# Medium test (continuous integration checks)
+runtest = '-L quick'
+
+modextrapaths = {'PYTHONPATH': 'lib/python%(pyshortver)s/site-packages'}
+
+sanity_check_commands = ["python -c 'import psi4'"]
+
+moduleclass = 'chem'
diff --git a/easybuild/easyconfigs/p/PSI4/PSI4-1.6.1_fix_cmake_release.patch b/easybuild/easyconfigs/p/PSI4/PSI4-1.6.1_fix_cmake_release.patch
new file mode 100644
index 000000000000..242c5f5c517e
--- /dev/null
+++ b/easybuild/easyconfigs/p/PSI4/PSI4-1.6.1_fix_cmake_release.patch
@@ -0,0 +1,95 @@
+# remove CMAKE_BUILD_TYPE check (beacuse it is set to EasyBuildRelease to avoid -O3 optimization flag)
+# November 02nd 2018 by B. Hajgato - (Free University Brussels - VUB)
+# Adopted to v1.3.2 by Åke Sandgren, HPC2N
+# Adopted to v1.6.1 by J. Sassmannshausen (Imperial College London/UK)
+
+diff --git a/psi4-1.6.1.orig/cmake/autocmake_safeguards.cmake b/psi4-1.6.1/cmake/autocmake_safeguards.cmake
+index 7c0a2a9..441080d 100644
+--- a/psi4-1.6.1.orig/cmake/autocmake_safeguards.cmake
++++ b/psi4-1.6.1/cmake/autocmake_safeguards.cmake
+@@ -19,8 +19,8 @@ endif()
+ string(TOLOWER "${CMAKE_BUILD_TYPE}" cmake_build_type_tolower)
+ string(TOUPPER "${CMAKE_BUILD_TYPE}" cmake_build_type_toupper)
+ 
+-if(NOT cmake_build_type_tolower STREQUAL "debug" AND
+-   NOT cmake_build_type_tolower STREQUAL "release" AND
+-   NOT cmake_build_type_tolower STREQUAL "relwithdebinfo")
+-    message(FATAL_ERROR "Unknown build type \"${CMAKE_BUILD_TYPE}\". Allowed values are Debug, Release, RelWithDebInfo (case-insensitive).")
+-endif()
++#if(NOT cmake_build_type_tolower STREQUAL "debug" AND
++#   NOT cmake_build_type_tolower STREQUAL "release" AND
++#   NOT cmake_build_type_tolower STREQUAL "relwithdebinfo")
++#    message(FATAL_ERROR "Unknown build type \"${CMAKE_BUILD_TYPE}\". Allowed values are Debug, Release, RelWithDebInfo (case-insensitive).")
++#endif()
+diff --git a/psi4-1.6.1.orig/external/upstream/dkh/CMakeLists.txt b/psi4-1.6.1/external/upstream/dkh/CMakeLists.txt
+index a42709f..754c918 100644
+--- a/psi4-1.6.1.orig/external/upstream/dkh/CMakeLists.txt
++++ b/psi4-1.6.1/external/upstream/dkh/CMakeLists.txt
+@@ -15,6 +15,7 @@ if(${ENABLE_dkh})
+         ExternalProject_Add(dkh_external
+             URL https://github.com/psi4/dkh/archive/v1.2.tar.gz
+             UPDATE_COMMAND ""
++            PATCH_COMMAND  sed -e "s/debug/easybuildrelease/" -i cmake/autocmake_safeguards.cmake
+             CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${STAGED_INSTALL_PREFIX}
+                        -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                        -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+diff --git a/psi4-1.6.1.orig/external/upstream/gau2grid/CMakeLists.txt b/psi4-1.6.1/external/upstream/gau2grid/CMakeLists.txt
+index 6e80ff3..8ca37f3 100644
+--- a/psi4-1.6.1.orig/external/upstream/gau2grid/CMakeLists.txt
++++ b/psi4-1.6.1/external/upstream/gau2grid/CMakeLists.txt
+@@ -15,6 +15,7 @@ else()
+         DEPENDS pybind11_external
+         URL https://github.com/dgasmith/gau2grid/archive/v2.0.7.tar.gz
+         UPDATE_COMMAND ""
++        PATCH_COMMAND  sed -e "s/debug/easybuildrelease/" -i cmake/autocmake_safeguards.cmake
+         CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${STAGED_INSTALL_PREFIX}
+                    -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                    -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+diff --git a/psi4-1.6.1.orig/external/upstream/gdma/CMakeLists.txt b/psi4-1.6.1/external/upstream/gdma/CMakeLists.txt
+index fb003a8..b8d0439 100644
+--- a/psi4-1.6.1.orig/external/upstream/gdma/CMakeLists.txt
++++ b/psi4-1.6.1/external/upstream/gdma/CMakeLists.txt
+@@ -15,6 +15,7 @@ if(${ENABLE_gdma})
+         ExternalProject_Add(gdma_external
+             URL https://github.com/psi4/gdma/archive/9d607d7.tar.gz  # v2.2.6-2-g9d607d7
+             UPDATE_COMMAND ""
++            PATCH_COMMAND  sed -e "s/debug/easybuildrelease/" -i cmake/autocmake_safeguards.cmake
+             CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${STAGED_INSTALL_PREFIX}
+                        -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                        -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+diff --git a/psi4-1.6.1.orig/external/upstream/libefp/CMakeLists.txt b/psi4-1.6.1/external/upstream/libefp/CMakeLists.txt
+index 2b4d047..8270404 100644
+--- a/psi4-1.6.1.orig/external/upstream/libefp/CMakeLists.txt
++++ b/psi4-1.6.1/external/upstream/libefp/CMakeLists.txt
+@@ -16,6 +16,7 @@ if(${ENABLE_libefp})
+             DEPENDS lapack_external
+             URL https://github.com/ilyak/libefp/archive/15cd7ce.tar.gz  # v1.5.0 + 10 (docs and a cmake lapack patch)
+             UPDATE_COMMAND ""
++            PATCH_COMMAND  sed -e "s/debug/easybuildrelease/" -i cmake/autocmake_safeguards.cmake
+             CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${STAGED_INSTALL_PREFIX}
+                        -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                        -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+diff --git a/psi4-1.6.1.orig/external/upstream/libint/CMakeLists.txt b/psi4-1.6.1/external/upstream/libint/CMakeLists.txt
+index 3e735d2..9a5325e 100644
+--- a/psi4-1.6.1.orig/external/upstream/libint/CMakeLists.txt
++++ b/psi4-1.6.1/external/upstream/libint/CMakeLists.txt
+@@ -15,6 +15,7 @@ else()
+     ExternalProject_Add(libint_external
+         # "git checkout" fails on Windows, because of "*" in filenames (e.g. basis set files)
+         URL https://github.com/loriab/libint/archive/libint_t.tar.gz
++        PATCH_COMMAND  sed -e "s/debug/easybuildrelease/" -i cmake/autocmake_safeguards.cmake
+         CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${STAGED_INSTALL_PREFIX}
+                    -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                    -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+diff --git a/psi4-1.6.1.orig/external/upstream/libxc/CMakeLists.txt b/psi4-1.6.1/external/upstream/libxc/CMakeLists.txt
+index 9e9b827..ada9c55 100644
+--- a/psi4-1.6.1.orig/external/upstream/libxc/CMakeLists.txt
++++ b/psi4-1.6.1/external/upstream/libxc/CMakeLists.txt
+@@ -19,6 +19,7 @@ else()
+         #GIT_REPOSITORY https://gitlab.com/libxc/libxc.git
+         #GIT_TAG 5.1.5
+         #UPDATE_COMMAND ""
++        PATCH_COMMAND  sed -e "s/debug/easybuildrelease/" -i cmake/autocmake_safeguards.cmake
+         CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${STAGED_INSTALL_PREFIX}
+                    -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                    -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
diff --git a/easybuild/easyconfigs/p/PSI4/psi4-pythonpath.patch b/easybuild/easyconfigs/p/PSI4/psi4-pythonpath.patch
new file mode 100644
index 000000000000..314a21567894
--- /dev/null
+++ b/easybuild/easyconfigs/p/PSI4/psi4-pythonpath.patch
@@ -0,0 +1,27 @@
+Adds the environment PYTHONPATH so modules like numpy get found
+Author: J. Sassmannshausen (Imperial College London/UK)
+diff --git a/psi4-1.6.1.orig/cmake/TestingMacros.cmake b/psi4-1.6.1/cmake/TestingMacros.cmake
+index 07074a7..9498db7 100644
+--- a/psi4-1.6.1.orig/cmake/TestingMacros.cmake
++++ b/psi4-1.6.1/cmake/TestingMacros.cmake
+@@ -46,7 +46,7 @@ macro(add_regression_test _name _labels)
+     )
+     set_tests_properties("${_name}"
+       PROPERTIES
+-        ENVIRONMENT PYTHONPATH=${PSILIB})
++        ENVIRONMENT PYTHONPATH=${PSILIB}:$ENV{PYTHONPATH})
+ 
+     if(labels)
+         set_tests_properties(${_name} PROPERTIES LABELS "${labels}")
+diff --git a/psi4-1.6.1.orig/tests/pytests/CMakeLists.txt b/psi4-1.6.1/tests/pytests/CMakeLists.txt
+index 39a92e3..15b6993 100644
+--- a/psi4-1.6.1.orig/tests/pytests/CMakeLists.txt
++++ b/psi4-1.6.1/tests/pytests/CMakeLists.txt
+@@ -14,6 +14,6 @@ endif()
+ 
+ # A single command to remake and run the pytest smoke tests
+ add_custom_target(pytest
+-                  COMMAND PYTHONPATH=${STAGED_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}${PYMOD_INSTALL_LIBDIR}
++	COMMAND PYTHONPATH=${STAGED_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}${PYMOD_INSTALL_LIBDIR}:$ENV{PYTHONPATH}
+                           ${Python_EXECUTABLE} -m pytest -rws -v -m smoke --capture=sys ${CMAKE_CURRENT_SOURCE_DIR}
+                   WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})