diff --git a/definition-files/ubuntu/Singularity.ubuntu-18.04-openmpi-4.0.5 b/definition-files/ubuntu/Singularity.ubuntu-18.04-openmpi-4.0.5
new file mode 100644
index 0000000..df94ed9
--- /dev/null
+++ b/definition-files/ubuntu/Singularity.ubuntu-18.04-openmpi-4.0.5
@@ -0,0 +1,134 @@
+Bootstrap: shub
+From: mkandes/naked-singularity:ubuntu-18.04
+
+%labels
+
+    APPLICATION_NAME ubuntu + openmpi
+    APPLICATION_VERSION 18.04 + 4.0.5
+    APPLICATION_URL https://www.open-mpi.org
+
+    AUTHOR_NAME Marty Kandes
+    AUTHOR_EMAIL mkandes@sdsc.edu
+
+    LAST_UPDATED 20210319
+
+%setup
+
+%environment
+
+    # Set Mellanox OFED version, operating system, and hardware platform
+    export MLNX_ROOT_URL='http://www.mellanox.com/downloads/ofed'
+    export MLNX_OFED_VERSION='4.7-3.2.9.0'
+    export MLNX_OS_VERSION='ubuntu18.04'
+    export MLNX_PLATFORM='x86_64'
+
+    # Set OpenMPI major, minor, and revision numbers, root and
+    # installation directories
+    export OMPI_ROOT_URL='https://download.open-mpi.org/release/open-mpi'
+    export OMPI_MAJOR='4'
+    export OMPI_MINOR='0'
+    export OMPI_REVISION='5'
+    export OMPI_VERSION="${OMPI_MAJOR}.${OMPI_MINOR}.${OMPI_REVISION}"
+    export OMPI_ROOT_DIR='/opt/openmpi'
+    export OMPI_INSTALL_DIR="${OMPI_ROOT_DIR}/${OMPI_VERSION}"
+
+    # Set paths to OpenMPI binaries and libraries
+    export PATH="${OMPI_INSTALL_DIR}/bin:${PATH}"
+    export LD_LIBRARY_PATH="${OMPI_INSTALL_DIR}/lib:${LD_LIBRARY_PATH}"
+
+%post -c /bin/bash
+
+    # Set operating system mirror URL
+    export MIRRORURL='http://us.archive.ubuntu.com/ubuntu'
+
+    # Set operating system version
+    export OSVERSION='bionic'
+
+    # Set system locale
+    export LC_ALL='C'
+
+    # Set debian frontend interface
+    export DEBIAN_FRONTEND='noninteractive'
+
+    # Upgrade all software packages to their latest versions
+    apt-get -y update && apt-get -y upgrade
+
+    # Install all dependencies and/or prerequisites for Mellanox OFED
+    apt-get -y install bison
+    apt-get -y install chrpath
+    apt-get -y install debhelper
+    apt-get -y install dpatch
+    apt-get -y install flex
+    apt-get -y install graphviz
+    apt-get -y install libnl-3-dev
+    apt-get -y install libnl-route-3-200
+    apt-get -y install tcl-dev
+    apt-get -y install tk-dev
+    apt-get -y install swig
+
+    cd /tmp
+
+    # Set Mellanox OFED version, operating system, and hardware platform
+    export MLNX_ROOT_URL='http://www.mellanox.com/downloads/ofed'
+    export MLNX_OFED_VERSION='4.7-3.2.9.0'
+    export MLNX_OS_VERSION='ubuntu18.04'
+    export MLNX_PLATFORM='x86_64'
+
+    # Download and install Mellanox OFED drivers and supporting
+    # libraries for userspace access to Ethernet, RDMA, and Infiniband. 
+    # https://docs.mellanox.com/pages/releaseview.action?pageId=15049785
+    wget "${MLNX_ROOT_URL}/MLNX_OFED-${MLNX_OFED_VERSION}/MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}.tgz"
+    tar -xf "MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}.tgz"
+    cd "MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}"
+    ./mlnxofedinstall --user-space-only --without-fw-update --force
+
+    cd /tmp
+
+    # Remove Mellanox OFED archive directory and tarball
+    rm -rf "MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}"
+    rm "MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}.tgz"
+
+    # Install additional tools
+    apt-get -y install numactl
+    apt-get -y install libnuma-dev
+
+    # Install OpenMPI dependencies
+    apt-get -y install zlib1g-dev
+
+    cd /tmp
+
+    # Set OpenMPI major, minor, and revision numbers, root and
+    # installation directories
+    export OMPI_ROOT_URL='https://download.open-mpi.org/release/open-mpi'
+    export OMPI_MAJOR='4'
+    export OMPI_MINOR='0'
+    export OMPI_REVISION='5'
+    export OMPI_VERSION="${OMPI_MAJOR}.${OMPI_MINOR}.${OMPI_REVISION}"
+    export OMPI_ROOT_DIR='/opt/openmpi'
+    export OMPI_INSTALL_DIR="${OMPI_ROOT_DIR}/${OMPI_VERSION}"
+
+    # Download, build, and install OpenMPI
+    wget "${OMPI_ROOT_URL}/v${OMPI_MAJOR}.${OMPI_MINOR}/openmpi-${OMPI_VERSION}.tar.gz"
+    tar -xf "openmpi-${OMPI_VERSION}.tar.gz"
+    cd "openmpi-${OMPI_VERSION}"
+    ./configure --prefix="${OMPI_INSTALL_DIR}" --without-verbs
+    make all install
+
+    cd /tmp
+
+    # Remove OpenMPI build directory and source tarball
+    rm -rf "openmpi-${OMPI_VERSION}"
+    rm "openmpi-${OMPI_VERSION}.tar.gz"
+
+    # Cleanup
+    apt-get -y autoremove --purge
+    apt-get -y clean
+
+    # Update database for mlocate
+    updatedb
+
+%files
+
+%runscript
+
+%test
diff --git a/definition-files/ubuntu/Singularity.ubuntu-18.04-openmpi-4.1.0 b/definition-files/ubuntu/Singularity.ubuntu-18.04-openmpi-4.1.0
new file mode 100644
index 0000000..cb0c679
--- /dev/null
+++ b/definition-files/ubuntu/Singularity.ubuntu-18.04-openmpi-4.1.0
@@ -0,0 +1,134 @@
+Bootstrap: shub
+From: mkandes/naked-singularity:ubuntu-18.04
+
+%labels
+
+    APPLICATION_NAME ubuntu + openmpi
+    APPLICATION_VERSION 18.04 + 4.1.0
+    APPLICATION_URL https://www.open-mpi.org
+
+    AUTHOR_NAME Marty Kandes
+    AUTHOR_EMAIL mkandes@sdsc.edu
+
+    LAST_UPDATED 20210319
+
+%setup
+
+%environment
+
+    # Set Mellanox OFED version, operating system, and hardware platform
+    export MLNX_ROOT_URL='http://www.mellanox.com/downloads/ofed'
+    export MLNX_OFED_VERSION='4.7-3.2.9.0'
+    export MLNX_OS_VERSION='ubuntu18.04'
+    export MLNX_PLATFORM='x86_64'
+
+    # Set OpenMPI major, minor, and revision numbers, root and
+    # installation directories
+    export OMPI_ROOT_URL='https://download.open-mpi.org/release/open-mpi'
+    export OMPI_MAJOR='4'
+    export OMPI_MINOR='1'
+    export OMPI_REVISION='0'
+    export OMPI_VERSION="${OMPI_MAJOR}.${OMPI_MINOR}.${OMPI_REVISION}"
+    export OMPI_ROOT_DIR='/opt/openmpi'
+    export OMPI_INSTALL_DIR="${OMPI_ROOT_DIR}/${OMPI_VERSION}"
+
+    # Set paths to OpenMPI binaries and libraries
+    export PATH="${OMPI_INSTALL_DIR}/bin:${PATH}"
+    export LD_LIBRARY_PATH="${OMPI_INSTALL_DIR}/lib:${LD_LIBRARY_PATH}"
+
+%post -c /bin/bash
+
+    # Set operating system mirror URL
+    export MIRRORURL='http://us.archive.ubuntu.com/ubuntu'
+
+    # Set operating system version
+    export OSVERSION='bionic'
+
+    # Set system locale
+    export LC_ALL='C'
+
+    # Set debian frontend interface
+    export DEBIAN_FRONTEND='noninteractive'
+
+    # Upgrade all software packages to their latest versions
+    apt-get -y update && apt-get -y upgrade
+
+    # Install all dependencies and/or prerequisites for Mellanox OFED
+    apt-get -y install bison
+    apt-get -y install chrpath
+    apt-get -y install debhelper
+    apt-get -y install dpatch
+    apt-get -y install flex
+    apt-get -y install graphviz
+    apt-get -y install libnl-3-dev
+    apt-get -y install libnl-route-3-200
+    apt-get -y install tcl-dev
+    apt-get -y install tk-dev
+    apt-get -y install swig
+
+    cd /tmp
+
+    # Set Mellanox OFED version, operating system, and hardware platform
+    export MLNX_ROOT_URL='http://www.mellanox.com/downloads/ofed'
+    export MLNX_OFED_VERSION='4.7-3.2.9.0'
+    export MLNX_OS_VERSION='ubuntu18.04'
+    export MLNX_PLATFORM='x86_64'
+
+    # Download and install Mellanox OFED drivers and supporting
+    # libraries for userspace access to Ethernet, RDMA, and Infiniband. 
+    # https://docs.mellanox.com/pages/releaseview.action?pageId=15049785
+    wget "${MLNX_ROOT_URL}/MLNX_OFED-${MLNX_OFED_VERSION}/MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}.tgz"
+    tar -xf "MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}.tgz"
+    cd "MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}"
+    ./mlnxofedinstall --user-space-only --without-fw-update --force
+
+    cd /tmp
+
+    # Remove Mellanox OFED archive directory and tarball
+    rm -rf "MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}"
+    rm "MLNX_OFED_LINUX-${MLNX_OFED_VERSION}-${MLNX_OS_VERSION}-${MLNX_PLATFORM}.tgz"
+
+    # Install additional tools
+    apt-get -y install numactl
+    apt-get -y install libnuma-dev
+
+    # Install OpenMPI dependencies
+    apt-get -y install zlib1g-dev
+
+    cd /tmp
+
+    # Set OpenMPI major, minor, and revision numbers, root and
+    # installation directories
+    export OMPI_ROOT_URL='https://download.open-mpi.org/release/open-mpi'
+    export OMPI_MAJOR='4'
+    export OMPI_MINOR='1'
+    export OMPI_REVISION='0'
+    export OMPI_VERSION="${OMPI_MAJOR}.${OMPI_MINOR}.${OMPI_REVISION}"
+    export OMPI_ROOT_DIR='/opt/openmpi'
+    export OMPI_INSTALL_DIR="${OMPI_ROOT_DIR}/${OMPI_VERSION}"
+
+    # Download, build, and install OpenMPI
+    wget "${OMPI_ROOT_URL}/v${OMPI_MAJOR}.${OMPI_MINOR}/openmpi-${OMPI_VERSION}.tar.gz"
+    tar -xf "openmpi-${OMPI_VERSION}.tar.gz"
+    cd "openmpi-${OMPI_VERSION}"
+    ./configure --prefix="${OMPI_INSTALL_DIR}" --without-verbs
+    make all install
+
+    cd /tmp
+
+    # Remove OpenMPI build directory and source tarball
+    rm -rf "openmpi-${OMPI_VERSION}"
+    rm "openmpi-${OMPI_VERSION}.tar.gz"
+
+    # Cleanup
+    apt-get -y autoremove --purge
+    apt-get -y clean
+
+    # Update database for mlocate
+    updatedb
+
+%files
+
+%runscript
+
+%test