Search this site. Navigation Home. Setting up ORCA. General Input. Restarting calculations. Geometry input. Visualization and printing.PHCK - Orca
RI and auxiliary basis sets. Effective Core Potentials. Numerical precision. SCF Convergence Issues. Semiempirical methods. Double-hybrid DFT.
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Broken-symmetry DFT. Relativistic approximations. Tutorial: Saddlepoint "TS" optimization via relaxed scan.
Minimum energy path calculations. Tutorial: NEB calculations. Molecular properties. Frozen core calculations. Extrapolation methods. Tutorial: Resonance Raman. Tutorial: Setting up the orbitals for a CAS calculation.
Localized orbital centroid analysis. FOD analysis. Molecular dynamics. Optimizing to a saddlepoint often informally referred to as a "transition state" is often a bit tricky. A relaxed surface scan is one way to find an approximate minimum energy path connecting 2 minima and the saddle-point is then located by eigenvector-following method. In this tutorial, we demonstrate first how to find a saddlepoint using a relaxed surface scan and an eigenvector-following saddlepoint optimization.
Production calculations would of course be performed at the DFT level at least use analytical Hessian in that case instead of the numerical one below. Using a cheap method like PM3 more accurate alternatives are HF-3c or PBEh-3c to crudely explore potential energy surfaces or try out and get familiar with surface scans and TS optimizations in ORCA, before switching to the more expensive method, is not a bad idea though.
Just keep in mind that the potential energy surfaces can sometimes be completely different and it may not always save time. In order for the TS-optimization jobs to work at all, one needs to have previously found a geometry close to the TS and guessing it is usually too hard. One way is to find an internal coordinate that resembles the real reaction coordinate sufficiently well and run a relaxed surface scan.
More sophisticated methods such as the nudged elastic band method require no pre-defined choice of the reaction coordinate.
Starting with the F - ion in 3.Privacy Terms. Quick links. Available for single point energy calculations and geometry optimizations using the analytical gradient. Offers a flag to only optimize hydrogen atom positions for crystal structure refinement. The thermostat is now able to apply temperature ramps during simulation runs. Added two new constraint types which keep centers of mass fixed or keep complete molecules rigid. Can now set limit for maximum displacement of any atom in a MD step, which can stabilize dynamics with poor initial structures.
Runs can be cleanly aborted by "touch EXIT". Fixed an issue which slowed down molecular dynamics after many steps. Stefan Grimme's xTB method can now be used in the MD module, allowing fast simulations of large systems. Miscellaneous Compute thermochemical corrections at different temperatures without recomputing the Hessian Fragments can now be defined in the geom block as simple lists Simpler input format for definition of atom lists and fragments, in particular useful for large atom lists basename.
Menu Content. User menu Username: Password: Remember me Register now!ORCA is a general-purpose quantum chemistry program package that features virtually all modern electronic structure methods density functional theory, many-body perturbation and coupled cluster theories, and multireference and semiempirical methods. It is a flexible, efficient and easy-to-use general purpose tool for quantum chemistry with specific emphasis on spectroscopic properties of open-shell molecules.
It features a wide variety of standard quantum chemical methods ranging from semiempirical methods to DFT to single- and multireference correlated ab initio methods. It can also treat environmental and relativistic effects. ORCA uses standard Gaussian basis functions and is fully parallelized.
Due to the user-friendly style, ORCA is considered to be a helpful tool not only for computational chemists, but also for chemists, physicists and biologists that are interested in developing the full information content of their experimental data with help of calculations. ORCA is able to carry out geometry optimizations and to predict a large number of spectroscopic parameters at different levels of theory.
Besides the use of Hartee Fock theory, density functional theory DFT and semiempirical methods, high level ab initio quantum chemical methods, based on the configuration interaction and coupled cluster methods, are included into ORCA to an increasing degree.
The suffix of ORCA input file can be anything - by convention unix input is. The general structure of a ORCA input file consist of several blocks:. Comments in the file start by a ' ' and can be closed by a second ' '.
Here is an example input file, which request a single point energy calculation on water:. In general the input is not case sensitive. However, inside strings the input is case sensitive under Linux systems. It can be run in either single-core or parallel MPI mode. Single core operations do not require any specifics. Above this, the overhead becomes signicant and the parallelization loses efficiency. Coupled cluster calculations usually scale well up to at least 8 processors but probably it is also worthwhile to try Explanation is embedded in these files.
Published works based on the usage of ORCA must contain appropriate citation. Neese, F.Version 2. Ruhr, Germany tccec mpi-mail. The case of ANOs. Orca Version 2 - Input Description 6. Arbitray Order Coupled Cluster Calculations IR Spectra Orca Version 2 - Input Description 7.
General Points The ORCA project is now more 10 years old and it is probably fair to say that the program has significantly matured over the past years. It is now used by more than individuals or research groups and is installed at dozens if not hundreds of supercomputer centers worldwide.
With this release, parallelization of the program has been completed. We feel strongly encouraged by the quickly growing user community. It is our pleasure to further develop the program for the benefit of the computational chemistry and spectroscopy communities. The further development of ORCA is generously supported by the Max Planck society and there is every reason to be optimistic about the future of this project.
Since when the group first moved to the university of Bonn, there has been a gradual shift in the focus of the development from special spectroscopy to more general purpose quantum chemistry.
This was made possible because the development group has considerably grown and highly talented and motivated students continued to bring in new features in and greatly improved existing ones. Efforts in these directions are continuing and will be intensified. However, with all developments in improved wavefunctions, speed und user friendliness, a major focus of the program will remain theoretical spectroscopy.
Finally, performance, parallelization robustness and user friendliness are subjects that continue to be high on our priority list. As always, we appreciate positive as well as negative feedback from our growing group of users and hope that you enjoy using the program as much as we enjoy developing it.ORCA technology simply mimics a natural digestion process. It works using the same principles that our body, and other living organisms are governed by.
ORCA creates the perfect thermophilic biological environment for the microorganisms to digest food waste into a liquid. ORCA is a hyperlocal, distributed alternative to the traditional truck and bin collection system. We deliver significant savings because we eliminate trucking from the process while significantly reducing the harmful emissions that come with truck traffic.
ORCA is pleased to deliver a solution that will assist our clients in mitigating the carbon footprint of their dining operation. ORCA designs, manufactures and installs the leading technology in the food waste recycling industry. ORCA uses mostly air, along with water and microbiology to turn your food waste into an environmentally safe liquid that goes down the drain and is disposed of using the existing sanitary sewer infrastructure.
Aerobic digestion begins once oxygen from the air is introduced to the mixture. Food waste is digested into smaller pieces, eventually transforming into a liquid. Liquid is filtered safely through a 0.
Once at the waste water treatment plant, the journey is not over. The liquid can then be used to create renewable, sustainable energy. Our technology creates meaningful cost savings for customers while diverting food waste from landfills. Landfill diversion reduces both carbon dioxide and methane gas emissions. ORCA also helps to increase labor efficiency by keeping employees in the kitchen and reducing the number of strains and sprains.
All ORCA models are equipped with onboard scales that will track the weight of every piece of food waste you put into it. The scales connect to our proprietary ORCA Portala personalized dashboard that will allow you to analyze real-time data, create customized reports, and look at the amount of food waste diverted over time. In order to keep everything running smoothly, we complement our technology with a service package to fit your needs. Inspired by nature, fueled by science.
ORCA is an innovative food waste solution. Introducing Baby Orca. See the latest addition to our product line! How our state-of-the-art technology works. Oxygen Aerobic digestion begins once oxygen from the air is introduced to the mixture.
Breakdown Food waste is digested into smaller pieces, eventually transforming into a liquid. Discharge Liquid is filtered safely through a 0.
The journey continues. No matter your size, there's an ORCA model to fit your needs. Which model is right for you? View Models. Industries served. Lodging Casinos Hotels Resorts.The Library is built on the philosophy that it is usually faster to get a new calculation up and running by seeing some example input for a calculation and modifying it rather than writing new input from scratch and looking up each keyword.
The website is based on input files which are in a simple-as-possible format, i. There are also tips and tricks and general recommendations on computational chemistry. Website traffic sessions per day since December Search this site. Navigation Home. Setting up ORCA. General Input. Restarting calculations. Geometry input. Visualization and printing. RI and auxiliary basis sets. Effective Core Potentials. Numerical precision. SCF Convergence Issues. Semiempirical methods. Double-hybrid DFT.
Broken-symmetry DFT. Relativistic approximations. Tutorial: Saddlepoint "TS" optimization via relaxed scan.
Minimum energy path calculations. Tutorial: NEB calculations. Molecular properties. Frozen core calculations. Extrapolation methods. Tutorial: Resonance Raman. Tutorial: Setting up the orbitals for a CAS calculation. Localized orbital centroid analysis. FOD analysis. Molecular dynamics.
Questions and comments regarding this site may be directed to Ragnar Bjornsson. Ragnar Bjornsson RB. Tobias Kraemer TK.A full documentation of the language was not yet published. For a first glimpse, please see the SANscript page. If you have suggestions on useful features which could be implemented in future releases of the ORCA MD module, feel free to contact me via email.
List of changes in the molecular dynamics module. Click on the tabs to see the changes in previous ORCA releases. Home C. ORCA 4. Offers a flag to only optimize hydrogen atom positions for crystal structure refinement.
The thermostat is now able to apply temperature ramps during simulation runs. Added two new constraint types which keep centers of mass fixed or keep complete molecules rigid. Can now set limit for maximum displacement of any atom in a MD step, which can stabilize dynamics with poor initial structures. Runs can be cleanly aborted by "touch EXIT". Fixed an issue which slowed down molecular dynamics after many steps. Stefan Grimme's xTB method can now be used in the MD module, allowing fast simulations of large systems.
Released in December Molecular dynamics simulations can employ Cartesian, distance, angle, and dihedral angle constraints, which are enforced by the RATTLE algorithm. The MD module features cells of several geometries cube, orthorhombic, parallelepiped, sphere, ellipsoidwhich can help to keep the system inside of a well-defined volume.
The cells have repulsive harmonic walls. The cells can be defined as elastic, such that their size adapts to the system. This enables to run simulations under constant pressure.
A restart file is written in each simulation step. With this file, simulations can be restarted to seamlessly continue useful for batch runs or if the job crashed.