nwchem: 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 Debian possible default full paths are:

/usr/bin/nwchem - from package: nwchem

You may install the required package with command apt-get install {package}

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