apbs-dx2mol: 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/bin/apbs-dx2mol - from package: apbs-tools

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

Error in other languages:
apbs-dx2mol: bevel nie gevind nie
apbs-dx2mol: comandă negăsită
apbs-dx2mol: comando não encontrado
apbs-dx2mol: commande introuvable
apbs-dx2mol: command not found
apbs-dx2mol: käsku ei ole
apbs-dx2mol: không tìm thấy lệnh
apbs-dx2mol: komanda nerasta
apbs-dx2mol: Kommando nicht gefunden.
apbs-dx2mol: kommandot finns inte
apbs-dx2mol: komut yok
apbs-dx2mol: nie znaleziono polecenia
apbs-dx2mol: níor aimsíodh an t-ordú
apbs-dx2mol: no se encontró la orden
apbs-dx2mol: no s'ha trobat l'ordre
apbs-dx2mol: opdracht niet gevonden
apbs-dx2mol: parancs nem található
apbs-dx2mol: perintah tidak ditemukan
apbs-dx2mol: príkaz nenájdený
apbs-dx2mol: příkaz nenalezen
apbs-dx2mol: команда не найдена
apbs-dx2mol: командата не е открита
apbs-dx2mol: 命令找不到
apbs-dx2mol: コマンドが見つかりません