cp2k.popt_openmpi: command not found

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

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

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/cp2k.popt_openmpi - from package: cp2k-openmpi

You may install the required package with command yum install {package}

Error in other languages:
cp2k.popt_openmpi: bevel nie gevind nie
cp2k.popt_openmpi: comandă negăsită
cp2k.popt_openmpi: comando não encontrado
cp2k.popt_openmpi: commande introuvable
cp2k.popt_openmpi: command not found
cp2k.popt_openmpi: käsku ei ole
cp2k.popt_openmpi: không tìm thấy lệnh
cp2k.popt_openmpi: komanda nerasta
cp2k.popt_openmpi: Kommando nicht gefunden.
cp2k.popt_openmpi: kommandot finns inte
cp2k.popt_openmpi: komut yok
cp2k.popt_openmpi: nie znaleziono polecenia
cp2k.popt_openmpi: níor aimsíodh an t-ordú
cp2k.popt_openmpi: no se encontró la orden
cp2k.popt_openmpi: no s'ha trobat l'ordre
cp2k.popt_openmpi: opdracht niet gevonden
cp2k.popt_openmpi: parancs nem található
cp2k.popt_openmpi: perintah tidak ditemukan
cp2k.popt_openmpi: príkaz nenájdený
cp2k.popt_openmpi: příkaz nenalezen
cp2k.popt_openmpi: команда не найдена
cp2k.popt_openmpi: командата не е открита
cp2k.popt_openmpi: 命令找不到
cp2k.popt_openmpi: コマンドが見つかりません