AutoTS: Perform Calculations Panel

Set up and run a transition state search. The setup involves providing a set of reactant and product structures, viewing the reactant and product complexes and an initial reaction path, adjusting these structures as necessary, then making settings and running the job.

To open this panel: click the Tasks button and browse to Quantum Mechanics → AutoTS.

Using the AutoTS: Perform Calculations Panel

The purpose of the AutoTS facility is to find a transition state that leads to a chemical change (rather than just a conformational change, which it attempts to eliminate). The transition state search is done by interpolating between reactants and products to find a guessed transition state. This guess is used in a search and, if successful, the nearest minima on both sides of the reaction are found, by using an intrinsic reaction coordinate (IRC) calculation, and compared to the input. This is done to verify that this transition state is in fact the one that connects the input structures. If the TS does not connect the input structures, additional connections between the reactants and products are searched for. If the TS search fails, the guess is improved in an attempt to converge the calculation. Finally a table is printed that summarizes the results. You can load the results in the AutoTS: View Results Panel by clicking the button for the entry. The output file is in the jobname/jobname_AutoTS subdirectory of the working directory, and is named jobname_full_path.mae.

Successful transition state searches depend critically on the quality of the input complexes and the initial guess at the transition state. If these are poor, you can try to manually improve the structures to increase the likelihood of success. A complex path or one in which there is considerable movement of peripheral structures is likely to produce problems in the search.

While AutoTS has the ability to search for multiple transition states that connect input reactants to products (i.e. multi-step reactions) the success rate is likely to be highest for simple, single-step reactions. The suggested strategy for using this tool for a multi-step reaction is to form a hypothesis for the mechanism of your reaction and then treat each step as a separate reaction.

Multiple reactions can be created, either by duplicating a reaction that is already in the panel and editing its structures, or by importing reactant and product structures. When the job is run, a subjob is created for each reaction. The subjobs can be distributed over multiple processors so that they run concurrently.

To write out the input file and a script for running the job from the command line, click the arrow next to the Settings button and choose Write. For information on command usage and options, see autots Command Help and Running AutoTS from the Command Line.

AutoTS: Perform Calculations Panel Features

Reaction naming, selection and storage controls

These controls allow you to name a reaction and save it or export it, and select a reaction to work with.

Reaction name text box

Provide a name for the reaction. The name is used on the reaction option menu, and to label the temporary entry group in the project that stores the structures.

Duplicate button

Duplicate the current reaction. The reaction is given a new default name, which is added to the option menu, and the structures for the original reaction are saved to the current working directory. This feature allows you to take a base reaction and easily make variations on it.

Export button

Export the current reaction to an AutoTS input file. This allows you to subsequently load the reaction using the reaction option menu.

New button

Create a new, empty reaction. The reaction is given a default name, which is added to the option menu.

Reaction option menu

Select the reaction that you want to work with. The choices are the saved reactions, the current (unsaved) reaction, or From file, which opens a file selector, so you can navigate to and choose an AutoTS input file. The reaction data is loaded from this file into the Project Table and the panel.

Set Up Reaction tab

In this tab you set up the reactants and the products for a reaction.

Reactants section
Products section

Set up the reactants and the products. The same tools are available for reactants and products.

Each reactant or product must be a single molecule. The main part of the section displays the 2D structure of each molecule in a table cell. At the top of the cell are a check box, which controls the inclusion of the structure in the Workspace (linked to the In column in the Entry List or Project Table), and Edit Structure(pencil icon) and Delete structure (X icon) buttons. The Edit Structure button opens the 2D Sketcher panel so you can edit the structure. The Delete Structure button deletes the molecule, which removes it from the panel and deletes its entry from the reaction entry group in the Project Table.

Sketch button

Click this button to sketch a reactant structure in the 2D Sketcher panel. When you have finished sketching the molecule, click Save to add it to the table. A 3D structure is generated from the 2D structure and added to the reaction entry group in the Project Table. You can also double-click in a blank part of the display area (not in a table cell) to open the 2D Sketcher panel.

You can set the charge and spin multiplicity for the molecule in this panel. If any of the atoms in the molecule have a formal charge, you cannot set the molecular charge, as it is determined from the sum of atomic charges. If there are no formal charges, you can set the overall charge on the molecule. If you set the spin multiplicity, you should make sure it is consistent with the number of electrons in the molecule. Note that the overall spin multiplicity of the reaction is set independently, in the Advanced Settings tab.

Import button

Import reactant or product structures. Each structure is split into individual molecules, and each molecule is then used as a reactant or product. Although there are no limits imposed on the number of molecules you can import, all molecules must be active participants in the reaction (not spectators), and reactions with more than 3 reactant or product molecules have not been well tested.

  • From File—Opens a file selector, so you can locate and load the file containing the structures. The file should contain only the reactants or the products.

  • From Project Table (n selected entries)—Use the structures that are selected in the Project Table.

  • From Workspace (n included entries)—Use the structures that are included in the Workspace.

  • From SMILES string—Opens the Import SMILES dialog box so you can enter a SMILES string for the structure. The string is converted into a 3D structure.

Preview Reaction Complex tab

Generate reactant and product complexes and a guess at the path, and adjust the structures of the complexes if necessary.

Generate Complexes button

Generate the pre-reactive (entrance) and post-reactive (exit) complexes. These complexes are used to generate a reaction path and transition state guess.

Generate Reaction Path button

Once the complexes are generated, click this button to generate a reaction path.

Complexes table

Lists the reaction complexes and the path, with a check box for including the structure in the Workspace.

Move Atoms button

Use the Workspace tools to adjust the structure of the complex. [Currently not functional; however, as the complexes are just project entries, you can simply include them in the Workspace and adjust them with the usual adjustment tools.]

Advanced Settings tab

Make settings for the reaction complexes, the reaction workflow, and for the individual Jaguar calculations performed in the workflow.

Reaction Options section

Set options for the reaction workflow.

Total spin multiplicity of reaction box

Specify the total spin multiplicity of the reacting system. This value must be provided, as it cannot in general be deduced from the spin multiplicities of the reactants or the products.

Optimize input molecules option

Optimize the structures of the reactant and product molecules separately.

Use templates option

Use stored templates to construct the transition state geometry and reaction path. A template consists of the transition state and the IRC-located endpoints of a successful transition-state search. The input structures are matched to the template structures and the transition state and reaction path are constructed with the help of the template. AutoTS has a default set of templates that can be used. To create your own templates for use in AutoTS, you can use the store_reaction_template Command Help utility.

Calculate energies at infinite separation option

Compute the energies of each reactant and product molecule as isolated molecules. By default, only the energy of the reactant and product complexes are computed. When this option is selected, the energy of reaction is also computed.

Also compute reaction free energies option

Compute the free energies of each reactant and product molecule as isolated molecules. By default, only the energy of the reactant and product complexes are computed. When this option is selected, the free energy of the reaction is also computed. This option involves a frequency calculation on the isolated molecules.

Use intrinsic reaction coordinate (IRC) option and menu

Perform a IRC calculation, and choose the method for calculating the IRC in the option menu:

  • Full—Run a full IRC calculation.

  • Three-Point—Set up an initial point on the IRC path in each direction, and then optimize the geometry for each structure to find the minimum.

  • LQA—use the Local Quadratic Approximation to calculate the IRC.

Apply fallback method if calculation fails option

Use artificial force induced reaction (AFIR) method to calculate a path from minima to minima if other methods fail.

Jaguar keywords option and text box

Select the option to specify any extra Jaguar gen section keywords for the calculations, as a comma-separated list of keyword=value settings. For information on these keywords, see The gen Section of the Jaguar Input File

Special options option and text box

Select the option to specify keyword settings for the script that is used to run the transition state search, as a comma-separate list of keyword=value settings.

Level of Theory section

These tools allow you to specify the default basis set and the default level of theory.

Theory text box and button

Click the button to select the level of theory. A small pane opens with controls for selecting the level of theory. The pane consists of a search text box, a filter button, and a list of available theoretical models. Typing in the text box narrows the list to items that contain the text. Clicking the filter button allows you to set options to restrict the list to certain models, e.g. range-corrected DFT. When you choose an item from the list, the pane closes and the text box (which is noneditable) shows the level of theory you chose.

Making a choice of functional sets the dftname keyword in the gen section of the input file.

See DFT Keywords in the Jaguar Input File for information on the density functionals.

Basis set text box and button

Click the button to select the basis set. A small pane opens with controls for selecting the basis set. The pane consists of a search text box, a filter button, and a list of basis sets. Typing in the text box narrows the list to basis set names that contain the text. Clicking the filter button allows you to set options to restrict the list to basis sets with certain features: ECP, diffuse functions, pseudospectral, relativistic, RI-MP2 compatible. When you choose a basis set from the list, the pane closes and the text box (which is noneditable) shows the basis set you chose.

If the basis set is not available for any of the structures in the Structures table, the cell in the Basis Set column for that structure is colored red. If a composite method is chosen in the Theory text box, the corresponding pre-defined basis set is automatically selected, and the Basis set text box cannot be modified.

See Basis Sets for information on the basis sets available.

Solvation section
Solvent model option menu

Choose the solvent model from this option menu. The default is PCM.

  • None—do not include solvation, run a gas phase calculation only.
  • PBF—use the standard Poisson-Boltzmann continuum solvation model. This model generally produces better energies than the PCM models.
  • PCM—use one of several polarizable continuum models for solvation. The PCM models generally produce smoother convergence in geometry optimizations than the PBF model. See PCM Model for more information on these models. Options for selection of the model (PCM model) and its parameters (PCM radii) are displayed when you choose this option.
  • SMD—use the Minnesota solvation model SMD [321]. This model can be used with all available solvents. Available for single-point, geometry optimization, and frequency calculations.
Solvent text box and button

Click the button to select the solvent. A small pane opens with controls for selecting the solvent. The pane consists of a search text box, a filter button, and a list of available solvents. Typing in the text box narrows the list to solvent names that contain the text. Clicking the filter button allows you to set options to restrict the list to solvents with certain features: common, halogenated, aromatic, hydrocarbon, carbonyl, polar, and non-polar solvents. When you choose a solvent from the list, the pane closes and the text box (which is noneditable) shows the solvent you chose. For pKa calculations, the only solvent choices are Water, and DMSO. Water is the default for all except CH and NH acids, whose default is DMSO.

See Solvation Keywords in the Jaguar Input File for a list of available solvents.

Conformational Sampling section
Use conformational search option

Select to perform a conformational search with MacroModel after locating transition states.

Job toolbar

Manage job submission and settings. See Job Toolbar for a description of this toolbar.

The Job Settings button opens the AutoTS: Perform Calculations - Job Settings Dialog Box, where you can make settings for running the job.

Status bar

The status bar displays information about the current job settings and status for the panel. The settings includes the job name, task name and task settings (if any), number of subjobs (if any) and the host name and job incorporation setting. The job status can include messages about job start, job completion and incorporation.

Use the Reset button to reset the panel to its default settings and clear any data from the panel. You can also reset the panel from the Job toolbar.

The status bar also contains the Help button , which opens the help topic for the panel in your browser. If the panel is used by one or more tutorials, hovering over the Help button displays a button, which you can click to display a list of tutorials (or you can right-click the Help button instead). Choosing a tutorial opens the tutorial topic.

Workflow Examples