gmolpro graphical user interface

gmolpro is a GTK-based graphical interface to Molpro that runs on Linux and macOS workstations. It supports the preparation of inputs through an expert system that interacts with Molpro’s registry of commands, methods, and basis sets, guiding the user toward feasible combinations of calculation types (single point, optimization, etc.), methods, basis sets, and options. Checks are implemented so that the geometry, charge, and spin are consistent, and only appropriate methods are selected. Reasonable default settings are provided so that an input can be quickly set up. It also provides a plain-text editor to allow further editing of existing job inputs. Molecular structures can be constructed and edited using an integrated builder derived from the PQSMol interface to the PQS package. It incorporates fragment libraries, force fields, and an optimization based on force fields. Jobs can then be submitted and managed on the local computer or a remote machine. Visualisation of results includes interactive display of structures, orbitals, property maps, and vibrational modes.

gmolpro requires

  1. a macOS (10.13 or later) or Linux (Ubuntu 18.04, Fedora 31, openSUSE 15.1 or openSUSE 15.2) workstation
  2. a locally-installed copy of Molpro 2020.2 or later. Note that on macOS, gmolpro starts without visiting shell initialisation scripts, so you need to make sure that molpro is found in the system path.
  3. for any remote systems on which you wish to launch jobs, Molpro 2020.2 or later. Although output from earlier versions of Molpro can be interpreted by gmolpro, jobs that it launches will fail immediately without output with an old or no version of Molpro.
  4. for remote systems where jobs are managed by a scheduler, an appropriate script that constructs and submits the job, with the name of the input file as its single argument, possibly preceded by options.

All files belonging to a particular calculation (input, output, geometry etc.), as well as additional data, are contained in a project, which is implemented as a filesystem directory (on macOS, a bundle). gMolpro automatically creates and maintains these projects. Project directories have extension .molpro, e.g. c2h2.molpro, but they may be accessed by the name without the extension. In the following, c2h2 is used as example project name.

gmolpro can be started either by typing gmolpro in a terminal window, or by launching the gmolpro application in the way that is usual on your system. When it opens, you are presented with the splash screen, which gives the opportunity to start a new project or open an existing one. Let's make a new one. We are first of all prompted to specify where to save it; from that point on, all changes to the project are written immediately to file without any save or similar commands. Next, we see two windows, denoted input (blue) and build (lilac). In the input window, we can set parameters for the calculation, whereas in the build window, we construct the molecular geometry. Let's construct a favourite molecule by taking it from the built-in library of molecular fragments. There is more you can do to build and edit the structure, but for now we will switch to the input window and run a calculation. We need to tell it at the minimum what method (let's choose B3LYP) to use, and for now we will just leave all other options alone. We can then use the Run button to launch the job. At this point, it is fine to close the project even if the job has not yet finished; we are then returned to the splash screen, where you can open another project, or quit.

gMolpro displays four different windows. The input (blue) and build (lilac) windows support preparation of a job, where as the output (white), view (brown) windows, which appear only once a job has started, show results. Switching between windows can be achieved using the Windows menu or with the keyboard shortcuts shown in the menu.

The window guides though the options for a calculation, constructing Molpro input for DFT and single-reference calculations. Generally, one should go through this window from top to bottom, since some settings depend on each other. Let's look at the possibilities. The geometry can be imported from an xyz file(Import Geometry) or generated using the Builder Window. Imported xyz files are not modified in the project, but can change during the calculation due to orientation or geometry optimization, and the optimized geometries can be exported and reused in subsequent calculations. The next important decision is the overall type of calculation - single geometry or structure optimization, with our without harmonic frequencies. We should then choose the method; let's try a correlated-wavefunction CCSD(T) calculation. The default for the Hamiltonian model is to use pseudopotentials to represent core electrons where appropriate, but you can choose instead to include all electrons, either non-relativistically or with a scalar relativistic Hamiltonian. There is also the possibility to specify whether and how core orbitals are included in the correlation treatment. The final principal choice is the basis set. The guided proposals for this are dependent on the method, hamiltonian and core correlation. You should first choose the overall quality - double, triple,… zeta - and then select within that if desired. It's also possible to specify the basis set element by element. The remainder of the input is associated with further options to control the running of the calculation and what it produces.

Further notes:

  • Density fitting is default for RHF, UHF, DFT, MP2, and local calculations but can be switched on or off by clicking the Density Fitting button (depending on the method).
  • Pseudopot. if available means to use (small core) pseudopotentials together with the associated basis sets when these are available (heavier elements), and all-electron basis sets for all other elements.
  • Core-correlation: mixed means to include outer core orbitals for elements left of the p-block in the periodic system. small means also to include (outer) core orbitals of other elements. Note that the basis sets depend on these settings.
  • Basis sets: first choose the quality (e.g. TZ, QZ), and then the default basis set. The recommended basis sets depend on the method. If the default basis is not available for some atom(s), or the use of other basis sets is desired for some atoms, use the element specific basis pulldown menu.
  • The right-hand pane showing the input is not directly editable when in “guided mode”. However, one can leave guided mode by clicking on this pane, and then any valid Molpro input can be entered. It is not possible to return to guided mode once it has been left. Externally-created projects also will open in this freehand mode. Other ways to manage projects include the sjef program or the pysjef_molpro and pysjef Python frameworks.
This window is used to build and pre-optimize molecular structures. On the right-hand side one can choose building blocks or fragments, which are then connected to the molecule in the left window. This is best illustrated by an example. Let’s build glycine, NH2CH2COOH. The easiest is of course to take it from the provided structures (click fragment - amino_acids - gly), but we can also build it step by step. Click Building Blocks, choose C in the periodic table, click on the symbol for C with 4 single bonds. The atom appears in the Segment Window. Click + in the lower icon list under the left window and click on the left window. The C-atom is copied to that position. Now continue to add the NH2 group: Click on Fragments, FUNCTIONAL_GROUPS, amino. Then click in the left window on the dangling bond to which you want to add the amino group. Next add the COOH group similarly. At this point, we have the full structure, but with some remaining dangling bonds that should be terminated with hydrogen. We do this by clicking on H in the upper left corner of the left window. Conformational and other adjustments can be carried out by, for example, rotating about bonds: click Rotate About a Bond in the bottom list of the left window, select the bond by clicking on it, then drag with the mouse to rotate. The structure can be preoptimized using a force field via the Optimize menu on top of the left window, or Optimize upper button.
output windowThis window displays, with continuous update, the raw output produced by Molpro once the job has started. A second tab is provided for inspecting the log file that is used, for example, in finite-displacement geometry gradient calculations.
The view window shows the final structure, ie after any geometry optimisation. It can also be used to display properties such as vibrational modes and orbitals, as well as the history of the geometry optimisation. In this example, a geometry optimisation and frequency calculation has already been carried out for glycine, and localised orbitals have been obtained. Notice that, as in the build window, you can alter the view, rotating by dragging with the mouse, or zooming using the centre mouse button (Linux) or command-key and mouse (macOS). First, let's check what happened in the optimisation by clicking the Optimization History button. We can play a movie of the optimising structure, or pick a particular point and export its geometry. The Vibrational Frequencies button shows the spectrum, from which individual modes can be selected and visualised. The Orbitals buttons brings up an energy level diagram from which individual orbitals can be selected. If more than one type of orbital has been calculated, you can choose the active set. Choose further display options from the Display/Orbital menu.
When you click Run in the input window, by default, the calculation will be run on your local machine. gmolpro always needs a local copy of Molpro (version at least 2020.1), and for many purposes, that is all you need. But support for running the calculation on another machine, and/or with non-default options such as process number and memory, is provided. One or more backends are defined in a file ~/.sjef/molpro/backends.xml. A backend is simply a specification of commands to launch, check and kill a job, and patterns to interpret status checks. One can then select which backend is assigned to the project, and this selection is remembered in the project's registry. The run command defined in the backend can be simply molpro, or might be the name of a custom script to present a job to a scheduler such as Slurm. The name of the command can be followed by parameters, which can also be specified in substitutable form, which lets you define per-project options to be used in the job submission and (optionally) their default values, e.g. for memory, number of parallel processes, job-scheduling parameters etc. These values can be modified in the “Run parameters” pulldown for a chosen backend. gmolpro will always do its best to render a project constructed with any version of Molpro, but for job submission, Molpro version 2020.1 or later is required on the backend.

Configuring a backend is straightforward, and requires usually just the hostname (which will be connected to with ssh, and which should be accessible without password) and the name of the run command. The run command script should be expect any specified options, followed by a single argument that is the name of the input to Molpro. The molpro command conforms to this; for more complex requirements, for example for constructing a batch job, a wrapper script will be needed. Further help is available on the detailed syntax of the backend.xml file.