need to install some base C++ headers for C++ library use

  if(LAMMPS_DEPS)

    add_dependencies(lammps ${LAMMPS_DEPS})

  endif()

  set(LAMMPS_CXX_HEADERS

    angle.h

    atom.h

    bond.h

    citeme.h

    comm.h

    compute.h

    dihedral.h

    domain.h

    error.h

    fix.h

    force.h

    group.h

    improper.h

    input.h

    kspace.h

    lammps.h

    lattice.h

    lmppython.h

    memory.h

    modify.h

    neighbor.h

    neigh_list.h

    output.h

    pair.h

    pointers.h

    region.h

    timer.h

    universe.h

    update.h

    variable.h)

  list(TRANSFORM LAMMPS_CXX_HEADERS PREPEND ${LAMMPS_SOURCE_DIR}/)

  set_target_properties(lammps PROPERTIES OUTPUT_NAME lammps${LAMMPS_LIB_SUFFIX})

  set_target_properties(lammps PROPERTIES SOVERSION ${SOVERSION})

  install(TARGETS lammps LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})

  install(FILES ${LAMMPS_SOURCE_DIR}/library.h DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/lammps)

  install(FILES ${LAMMPS_CXX_HEADERS} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/lammps)

  configure_file(pkgconfig/liblammps.pc.in ${CMAKE_CURRENT_BINARY_DIR}/liblammps${LAMMPS_LIB_SUFFIX}.pc @ONLY)

  install(FILES ${CMAKE_CURRENT_BINARY_DIR}/liblammps${LAMMPS_LIB_SUFFIX}.pc DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)

  configure_file(FindLAMMPS.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/FindLAMMPS${LAMMPS_LIB_SUFFIX}.cmake @ONLY)