What does BSSE mean in UNCLASSIFIED
Basis Set Superposition Error (BSSE) is a type of error that arises from the use of an incomplete basis set in ab initio molecular orbital calculations. This error can lead to inaccurate results or unexpected outcomes when comparing different calculations involving the same molecules at different levels of detail. In order to minimize BSSE, one must choose an appropriate basis set for the system being studied, as well as incorporate advanced techniques such as counterpoise corrections.
BSSE meaning in Unclassified in Miscellaneous
BSSE mostly used in an acronym Unclassified in Category Miscellaneous that means Basis Set Superposition Error
Shorthand: BSSE,
Full Form: Basis Set Superposition Error
For more information of "Basis Set Superposition Error", see the section below.
Explanation
In quantum chemistry, BSSE occurs when two or more molecular systems are compared using different levels of basis sets. The level of detail in a basis set is an important factor in determining how accurately a calculation predicts an energy value. If two different energy levels are obtained by using different basis sets, then the difference between them could be attributed to this phenomenon. BSSE is caused by interactions between electrons that have been split up into two molecular systems, which are not accounted for in the original grid used for a single molecule's energy level. When each molecule is considered independently in a calculation, its full electron-electron repulsion (EER) is calculated correctly; however, when two molecules interact with each other (e.g., in dimers), part of their interaction will be ignored due to the incompleteness of the original grid size used for the single molecule study. As a result, this neglected EER will cause differences in energies obtained when comparing various studies involving multiple molecules and/or monomers.
Counterpoise Corrections
The most common approach to addressing BSSE involves a technique called counterpoise corrections (CPC). CPC involves including additional terms in the calculation that account for the EERs that were previously left out due to incomplete basis sets being used. By doing so, it ensures that all contributions from electron-electron repulsion effects are included and taken into consideration during calculations involving multiple molecules or monomers interacting with each other. This helps reduce errors associated with BSSE and yields more accurate results overall.
Essential Questions and Answers on Basis Set Superposition Error in "MISCELLANEOUS»UNFILED"
What is Basis Set Superposition Error (BSSE)?
Basis Set Superposition Error (BSSE) is an error that occurs when using quantum chemical methods to calculate the interaction energy of two or more isolated molecules. It occurs when the basis set employed for the calculation of each molecular fragment does not properly account for electron correlation in the other, resulting in a distorted total energy value.
How does BSSE affect calculations?
When BSSE is present, calculated energies will be too low due to improper treatment of electron correlation between molecules, leading to errors in physical and chemical properties derived from these energies.
How Can I Avoid BSSE Errors?
The best way to avoid Basis Set Superposition Errors is to ensure that all subsystems are consistently described and treated with the same type and size of basis sets. This will help ensure accurate results.
Are There any Alternative Methods for Calculating Energies?
Yes, there are alternative methods such as multi-configurational self consistent field (MCSCF) or complete active space self consistent field (CASSCF). These methods attempt to more accurately treat electron correlation by including greater effects from electronic orbital interactions than traditional computational chemistry methods.
Is BSSE Parameter Free?
Unfortunately no, BSSE requires parameters such as orbital exponents, bond distances and angles for accurate calculations.
Are Computational Chemistry Methods always affected by BSSE?
Not necessarily; some methods may account for this issue better than others. For example, MC-SCF or CAS-SCF can provide more robust treatment of intermolecular electron correlations than traditional post-Hartree Fock theory approaches. However, even when using these methods though, it's always good practice to check if your results could be affected by BSSE before relying on them.
How do I interpret my results if BSSE is present?
If you find that your results have been affected by Basis Set Superposition Error then it's important to recognize they may not be reliable indicators of real physical observables. Instead, use other methods such as MC-SCF/CASS CF and consider other explanations for discrepancies between your results and experimentally observed values.
What Else Should I Keep In Mind With Respect To BSSE?
One should keep in mind that while completely removing the influence of basisset superposition error is often impossible due to practical constraints on resources and time available for calculations, using sufficiently large quality basis sets can help reduce its effect significantly.
Final Words:
In conclusion, Basis Set Superposition Errors (BSSE) can lead to inaccurate results or unexpected outcomes when performing quantum chemistry calculations on molecules using incomplete basis sets. To address this issue, counterpoise corrections can be utilized to take EERs missed out due to limited grid sizes into account and ensure more precise outcomes.
BSSE also stands for: |
|
| All stands for BSSE |