message: Only enable MPI if explicitly requested
  Linking in MPI may cause issues with Python bindings.
diff: @@ -123,10 +123,12 @@ endif()
  set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-attributes")
  -# check MPI status
  -# if MPI_CXX_COMPILER is not empty and cmake can find MPI
  +# NOTE: to enable MPI, need to configure CMAKE with -DXACC_ENABLE_MPI=TRUE
  +# (some XACC Python binding is not compatible with MPI, hence not building with MPI as default)
  +# Check MPI status
  +# if MPI_CXX_COMPILER is not empty and XACC_ENABLE_MPI is set
  # turn MPI_ENABLED on
  -if(NOT MPI_CXX_COMPILER STREQUAL "" OR XACC_ENABLE_MPI)
  +if(NOT MPI_CXX_COMPILER STREQUAL "" AND XACC_ENABLE_MPI)
  find_package(MPI)
  if(MPI_FOUND)
  set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DMPI_ENABLED")
  