GMXRC.bash: 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/GMXRC.bash - from package: gromacs-common

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

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