Installation

Here we go through the steps required to install all the parts and software that are needed to perform global searches with Quantum Espresso and ROMEO. Afterwards continue with the Tutorial.

Quantum Espresso

Install the version of Quantum Espresso with constrained occupations on each cluster or computer you want to perform the calculations on. This can be done through:

git clone https://gitlab.com/louisponet/q-e/ qe-occupations
cd qe-occupations
git checkout broyden_constraints

Followed by the standard commands that are required to install Quantum Espresso.

Julia

Download and install the latest version of Julia on the computer you are going to use to orchestrate the search, e.g. your personal workstation.

RomeoDFT.jl

Next we install the main driver software which for now is not publicly available, so some steps are required.

Begin by starting a julia REPL session, and execute:

using Pkg
Pkg.add("RomeoDFT")

or press the ] key to enter the julia pkg REPL mode and type add RomeoDFT. The package is now being intialized, sit back grab a coffee, this takes a long time (~5-10 min).

To update to a newer version you can do

using Pkg
Pkg.update("RomeoDFT")

or up RomeoDFT in the pkg REPL mode.

ROMEO executable

After having performed the above steps, there should be the romeo executable in ~/.julia/bin. You can use it as, e.g. ~/.julia/bin/romeo -h.

RemoteHPC Configuration

Next we configure the Servers, Execs and Environments that represent where, what and how executables can be ran on the remote clusters. In our case the qe-occupations/bin/pw.x executable.

From inside a shell, execute

romeo configure

Server

Use the arrow keys and enter to select Server. A Server represents a computer or cluster where executables can be ran. Your local computer is configured automatically so if you want to run everything locally, you can skip this step. Give the server a name that is used to load it later, and insert your username and domain that correspond to the ssh commands you use to connect to the cluster where you installed qe-occupations (e.g. ssh lponet@cscs.ch would mean username = lponet, domain = cscs.ch).

If you plan to run on multiple clusters, you can add them one after the other. For now, however, each Searcher runs on a single Server.

If you configured a new Server, go out of the configuration at this point and run romeo server start <name of new server> then run romeo configure again.

Exec

Next select Exec from the menu. Read carefully the documentation that is printed, enter a name (for example qe-occupations), select the Server that corresponds to where you installed the patched QuantumESPRESSO. After pressing enter, an editor will open with a representation of the Exec with some fields already filled in. Complete the remaining fields, especially path which should be the absolute directory of the qe-occupations/bin/pw.x executable on the remote Server. Again, read the Documentation that is printed below the fields to help filling out the remaining information.

Environment

An environment essentially represents the #SBATCH commands of a slurm job script, or similar. Carefully read the documentation and fill out the fields similar to above.

Pseudo Potentials

Finally we set up a set of pseudopotentials. For our intention, we install them locally. First download and unpack your favorite set of pseudopotentials into a local directoyr, then supply the directory during the configuration of a PseudoSet. Behind the scenes it will read through the directory you specified and resolve element names for the files in that directory that have the .UPF extension.

You're now ready to start the Orchestrator and run your first Searcher.