tkmolrender: 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 Debian possible default full paths are:

/usr/bin/tkmolrender - from package: mpqc-support

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