mpic++.mpich: 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 Debian possible default full paths are:

/usr/bin/mpic++.mpich - from package: libmpich-dev

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