mpmetis64: 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
/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/bin/mpmetis64 - from package: metis64

You may install the required package with command yum install {package}
Error in other languages:
mpmetis64: bevel nie gevind nie
mpmetis64: comandă negăsită
mpmetis64: comando não encontrado
mpmetis64: commande introuvable
mpmetis64: command not found
mpmetis64: käsku ei ole
mpmetis64: không tìm thấy lệnh
mpmetis64: komanda nerasta
mpmetis64: Kommando nicht gefunden.
mpmetis64: kommandot finns inte
mpmetis64: komut yok
mpmetis64: nie znaleziono polecenia
mpmetis64: níor aimsíodh an t-ordú
mpmetis64: no se encontró la orden
mpmetis64: no s'ha trobat l'ordre
mpmetis64: opdracht niet gevonden
mpmetis64: parancs nem található
mpmetis64: perintah tidak ditemukan
mpmetis64: príkaz nenájdený
mpmetis64: příkaz nenalezen
mpmetis64: команда не найдена
mpmetis64: командата не е открита
mpmetis64: 命令找不到
mpmetis64: コマンドが見つかりません