Dear all, In continuation with my previous email, I got success in running quantum espresso on my cluster. But now I am facing another problem. with the command mpiexec -f hosts -n 10 ./pw.x -i relax2.in > out.out & QS run perfectly, but as I increase the number of core like this mpiexec -f hosts -n 30 ./pw.x -i relax2.in > out.out & it gives an error mpiuser@master:~/qe-29-11/bin$ mpiexec -f hosts -n 30 ./pw.x -i relax2.in > out.out & [4] 2131 mpiuser@master:~/qe-29-11/bin$ ./pw.x: symbol lookup error: ./pw.x: undefined symbol: mpi_initialized_ ./pw.x: symbol lookup error: ./pw.x: undefined symbol: mpi_initialized_ ./pw.x: symbol lookup error: ./pw.x: undefined symbol: mpi_initialized_ ./pw.x: symbol lookup error: ./pw.x: undefined symbol: mpi_initialized_ ./pw.x: symbol lookup error: ./pw.x: undefined symbol: mpi_initialized_ ./pw.x: symbol lookup error: ./pw.x: undefined symbol: mpi_initialized_ ./pw.x: symbol lookup error: ./pw.x: undefined symbol: mpi_initialized_ ./pw.x: symbol lookup error: ./pw.x: undefined symbol: mpi_initialized_ However I have recent hydra supported version of mpich on all the nodes I request you all to kindly help me to overcome this Problem. with regards Haider abbas Department of Physics Manav Rachna University Faridabad, Haryana, India