cht: 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/cht - from package: chemtool

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

On Debian possible default full paths are:

/usr/bin/cht - from package: chemtool

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

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