excitingmpi_openmpi: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/lib64/openmpi/bin/excitingmpi_openmpi - from package: exciting-openmpi

You may install the required package with command yum install {package}
Error in other languages:
excitingmpi_openmpi: bevel nie gevind nie
excitingmpi_openmpi: comandă negăsită
excitingmpi_openmpi: comando não encontrado
excitingmpi_openmpi: commande introuvable
excitingmpi_openmpi: command not found
excitingmpi_openmpi: käsku ei ole
excitingmpi_openmpi: không tìm thấy lệnh
excitingmpi_openmpi: komanda nerasta
excitingmpi_openmpi: Kommando nicht gefunden.
excitingmpi_openmpi: kommandot finns inte
excitingmpi_openmpi: komut yok
excitingmpi_openmpi: nie znaleziono polecenia
excitingmpi_openmpi: níor aimsíodh an t-ordú
excitingmpi_openmpi: no se encontró la orden
excitingmpi_openmpi: no s'ha trobat l'ordre
excitingmpi_openmpi: opdracht niet gevonden
excitingmpi_openmpi: parancs nem található
excitingmpi_openmpi: perintah tidak ditemukan
excitingmpi_openmpi: príkaz nenájdený
excitingmpi_openmpi: příkaz nenalezen
excitingmpi_openmpi: команда не найдена
excitingmpi_openmpi: командата не е открита
excitingmpi_openmpi: 命令找不到
excitingmpi_openmpi: コマンドが見つかりません