Q-Chem Installation on Linux/Mac/AIX -- a step-by-step Guide

(last edited on 8/02/2016, email support@q-chem.com for questions)

1. Before installing Q-Chem, please make decisions on the following questions.

Which directory do you want to use as Q-Chem Top directory (QC). On a cluster environment Q-Chem has to be installed on a network shared directory, e.g., NFS shared drive.

Which directory to store Q-Chem scratch files (QCSCRATCH). Same as QC, on a cluster environment QCSCRATCH must be a network shared directory.

Which local directory to use for Q-Chem scratch files (QCLOCALSCR). The specification of QCLOCALSCR is not always required. Its use is for performance purpose but the actually performance improvement is not guaranteed. Unlike QC or QCLOCALSCR, QCLOCALSCR must be completely local. (Notes: /tmp is usually used in Linux for other purposes thus NOT recommended as QCLOCALSCR.)

Does the passwordless ssh work among the computing nodes? If not you should try setting it up. The instructions below might work for you.

+ Generate the ssh key pair using ssh-keygen (hit enter all the way)

ssh-keygen -t rsa -N "" -C ""

+ Copy your public key (~/.ssh/id_rsa.pub) to file ~/.ssh/authorized_keys and set proper permission for ~/.ssh directory.

cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 700 ~/.ssh
chmod 600 ~/.ssh/id_rsa
chmod 644 ~/.ssh/id_rsa.pub

+ Consult your system admin if there is further question about passwordless ssh setup.

2. In the following part of the tutorial we will first install Q-Chem in directory /usr/local/qchem40 as the root user. However, root priviledge is not required for Q-Chem installation. In your own setup you should also choose your own Q-Chem installation directory.

After installation I will also log in as user 'distrib' and set proper shell environment to run Q-Chem.

As the root user I will use the information below for Q-Chem installation.

host list : dellman dellman2
/dftman/home is nfs mounted shared directory
QC : /dftman/home/local/qchem40
QCSCRATCH : /dftman/home/scratch
QCLOCALSCR: (do not use)

User 'distrib' does the following (in csh/tcsh) to setup shell environment.

setenv QC /usr/local/qchem40
source $QC/qcevn.csh
setenv QCSCRATCH /dftman/home/scratch/distrib

Note that root did not setup passwordless ssh so we need to enter the password manually to log into dellman and dellman2 and obtain the SIDs. User distrib has passwordless ssh setup so he could run the calculations without being prompted for password.

3. Step-by-step screenshot for Q-Chem installation on Linux

wget http://www.q-chem.com/download/qcinstall/qcinstall.sh
chmod +x qcinstall.sh

[Step 1. Select QC directory and binary]

linux installation screenshot 01

[Step 2. Runtime environment specification]

linux screenshot 2

[Step 3. Registration -- MUST provide valid Email address]

linux installation screenshot -- registration

[Step 4. License data collection and submission]

linux installation screenshot -- license data gathering

linux installation screenshot 5

linux installation screen shot 1

[Step 5. User distrib set the runtime environment in the shell and run a test job]

linux installation screen shot 6