Quantemol

Quantemol Ltd is based in University College London initiated by Professor Jonathan Tennyson FRS and Dr. Daniel Brown in 2004. The company initially developed a unique software tool, Quantemol-N, which provides full accessibility to the highly sophisticated UK molecular R-matrix codes, used to model electron polyatomic molecule interactions. Since then Quantemol has widened to further types of simulation, with plasmas and industrial plasma tools, in Quantemol-P and Quantemol-D.

Quantemol-N

The Quantemol-N software system has been developed to simplify use of UK R-matrix codes. It provides an expert interface for non specialists to perform ab initio electron-molecule scattering calculations. Quantemol-N calculates a variety of observables for electron molecule collisions including:

• Elastic cross sections
• Electronic excitation cross sections
• Electron impact dissociation rates
• Resonance parameters
• Radial charge density calculation
• Dissociative electron attachment cross sections
• Ionisation cross sections
• Differential cross sections
• Momentum transfer sections
• Vibration excitation cross sections

Applicable simulations

Quantemol-N is capable of tackling a variety of problems;

• Closed shell molecules
• Open shell molecules, and radicals
• Neutral and positively charged species
• Molecules of up to 17 atoms. (Neopentane has been successfully simulated, with improvements allowing more atoms in the future, and rapid movement towards Biomolecules)

Accuracy

A study on the key benchmark molecule; water, gave results more accurate than obtainable experimentally (Faure et al. 2004).

Experimentally, there are problems measuring large cross sections at low angles; this applies to any molecule with a large dipole moment. Being a simulation, this is not a problem for Quantemol-N.

Relevant Publications

• Quantemol-N: an expert system for performing electron molecule collision calculations using the R-matrix method

Jonathan Tennyson, Daniel B. Brown, James J. Munro, Iryna Rozum, Hemal N. Varambhia and Natalia Vinci

Journal of Physics: Conference Series 86, 012001 (2007)

doi: 1742-6596/86/1/012001

• Calculations of Cross Sections Data for Scattering of Electrons on HBr

Radmilovic-Radjenovic M, Petrovic ZL,

ACTA PHYSICA POLONICA A, 117 (2010),745-747

• Electron-impact rotational excitation of the carbon monosulphide (CS) molecule

Varambhia HN, Faure A, Graupner K, et al.

Monthly Notices of the Royal Astronomical Society, 403 (2010), 1409-1412

• Cross-sections for the scattering of electrons with BF3

M. Radmilovic-Radjenovic, H. N. Varambhia, M. Vranic, J. Tennyson, Z. Lj. Petrovic.

Publ. Astron. Obs. Belgrade No. 84 (2008), 57-60

• R-matrix calculations of low-energy electron alkane collisions

Hemal N. Varambhia, James J. Munro and Jonathan Tennyson

International Journal of Mass Spectrometry, 271, 1-7 (2008)

• Electron collision with the HCN and HNC molecules using the R-matrix method

Hemal N. Varambhia and Jonathan Tennyson

Journal of Physics B: Atomic, Molecular and Optical Physics, 40, 1211-1223 (2007)

• Tool opens door to quantum modelling

29 March 2005, by Harry Yeates, Electronics Weekly

• Quantemol-N from plasma etch and lasers to earth’s ionosphere

15 March 2005, III-Vs Review

Quantemol-P

The etching of silicon wafers using gaseous plasmas underpins the rapid advance in computer technology that has powered the global economy, and will continue to do so for the foreseeable future. Currently, experimental testing is used to establish the relevant plasma mixes to generate the desired etch. Such testing is an expensive and time-consuming process even for relatively minor improvements in the processes. Simulation allows much of this process can be done outside of the reactor at reduced cost and improved efficiency. Quantemol-P provides users with a means to simulate these processes.

One of the key fundamental processes in etch plasmas is the collision of low-energy electrons with molecules. But for many years the associated molecular data has been missing from the plasma researchers' toolkit. Measurements of these collisions are both expensive and difficult to perform, and their theoretical determination requires the use of sophisticated procedures based on the application of quantum mechanics.

Program use

Quantemol-P assists in the research for new plasma recipes and optimizes given processes by simulating etch machines. The simulation inputs used match those of the plasma processing tools: e.g. power, pressure, gas flow rate, time, volume.

The program couples molecular data and plasma models to provide full information on the various plasma processes. This gives users more insight into the problem than usually obtainable.

A variety of technical plasmas can be simulated; including plasma etch reactors, plug-flow reactors and well-mixed reactors.

The plasma model in Quantemol-P is based on the zero-dimensional global-kinetics simulation code GLOBALKIN developed over a number of years by Kushner and co-workers.

Relevant Publications

• Global plasma simulations using dynamically generated chemical models

James J. Munro and Jonathan Tennyson

Journal of Vacuum Science and Technology A, 26, 865 (2008)

Quantemol-D

The development of new machinery underpins the development of new technology, as without newer, more advanced machines large scale manufacturing is not possible. Traditionally the development of such machinery is costly and wasteful, with many iteration cycles throughout the design process.

With the Quantemol-D software the machine design can be driven by high-level physics based simulation, leading to fewer physical iterations of the machine. Thus a cheaper, more efficient design process is created, which also has less impact on the environment.

The software builds upon the respected Hybrid Plasma Equipment Model (HPEM) codes developed by leading plasma physicist Professor Mark Kushner and others, adding a number of needed systems for both expert and non-expert users. Quantemol-D includes user interface enhancements, extensive documentation and support, data visualisation, analysis, job control, batch process and design of experiment support.

See also

3

External links

• Quantemol Official Site
• Quantemol-N: an expert system for performing electron molecule collision calculations using the R-matrix method
• Calculations of Cross Sections Data for Scattering of Electrons on HBr
• Electron-impact rotational excitation of the carbon monosulphide (CS) molecule
• Cross-sections for the scattering of electrons with BF3
• R-matrix calculations of low-energy electron alkane collisions
• Electron collision with the HCN and HNC molecules using the R-matrix method
• Tool opens door to quantum modelling
• Quantemol-N from plasma etch and lasers to earth’s ionosphere
• Global plasma simulations using dynamically generated chemical models