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Record W7132940009

Investigating chemical reactions using computer simulations

2002· dissertation· W7132940009 on OpenAlexfundno aff
Radu Iftimie

Bibliographic record

VenueTSpace · 2002
Typedissertation
Language
FieldChemistry
TopicChemical Reaction Mechanisms
Canadian institutionsnot available
FundersMinistère de l’Éducation, Gouvernement de l’Ontario
KeywordsAb initioMolecular dynamicsElectronic structureMonte Carlo methodQuantumAb initio quantum chemistry methodsTransition state theoryChemical reactionMolecular mechanics
DOInot available

Abstract

fetched live from OpenAlex

Although proton-transfer reactions are ubiquitous in chemistry and biology, their theoretical study is limited by number of difficulties. Some of the practical challenges involving the study of proton-transfer reactions include the fact that accurate descriptions of hydrogen-bonded systems require time-consuming ab initio electronic structure methods. Computer time limitations become particularly relevant when investigating “rare events” such as chemical reactions, especially when the reactions are accompanied by substantial differences in the structure of the solvent. In addition, the proton is the lightest nucleus and nuclear quantum effects must be described adequately in proton-transfer reactions. The problems mentioned above are addressed by proposing methodological improvements to calculate reaction rates for proton-transfer reactions. A new ab initio Monte Carlo algorithm is proposed in which a much faster molecular mechanics potential “guides” the slow ab initio electronic structure simulation resulting in significantly more efficient sampling schemes compared to the more familiar ab initio molecular dynamics methods. The molecular mechanics guided sampling method is generalized to incorporate nuclear quantum effects via centroid transition state theory and solvent effects via hybrid quantum mechanics-molecular mechanics methods. The use of the molecular mechanics based importance function method is exemplified in a study of model intra-molecular proton-transfer reactions which investigates how molecular mechanics potentials should be created in order to predict kinetic isotope effects and reaction mechanisms correctly, and to understand the conditions in which atoms other than the hydrogen atom should be treated quantum-mechanically.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.

metaresearch head score (Codex)0.001
metaresearch head score (Gemma)0.002
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Simulation or modeling · Consensus signal: Simulation or modeling
GenreCandidate signal: Empirical · Consensus signal: none
Teacher disagreement score0.008
Threshold uncertainty score0.016

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0010.002
Meta-epidemiology (narrow)0.0010.000
Meta-epidemiology (broad)0.0010.001
Bibliometrics0.0010.001
Science and technology studies0.0010.001
Scholarly communication0.0010.001
Open science0.0010.001
Research integrity0.0010.001
Insufficient payload (model declined to judge)0.0050.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.060
GPT teacher head0.357
Teacher spread0.297 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designSimulation or modeling
Domainnot available
GenreEmpirical

How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".

Quick stats

Citations0
Published2002
Admission routes1
Has abstractyes

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