packmol_solvate: 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/packmol_solvate - from package: packmol

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

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