Spin-state energetics of metallocenes: How do best wave function and density functional theory results compare with the experimental data?

2021 ◽  
Vol 23 (1) ◽  
pp. 151-172
Author(s):  
Gabriela Drabik ◽  
Janusz Szklarzewicz ◽  
Mariusz Radoń
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Wave Function ◽  
Spin State ◽  
Quantum Chemical ◽  
Density Functional ◽  
Chemical Methods ◽  
Functional Theory ◽  
Quantum Chemical Methods

Benchmarking quantum-chemical methods against experiment-derived spin-state energetics of metallocenes.

Halogen bonded supramolecular capsules: a challenging test case for quantum chemical methods

2016 ◽  
Vol 52 (64) ◽  
pp. 9893-9896 ◽  
Author(s):  
Rebecca Sure ◽  
Stefan Grimme
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
State Of The Art ◽  
Test Case ◽  
Binding Affinities ◽  
Chemical Methods ◽  
Functional Theory ◽  
Quantum Chemical Methods

By state-of-the-art dispersion corrected density functional theory, the complexation properties of a recently synthesized halogen-bonded capsule with about 400 atoms are investigated and predictions for improved binding affinities are made.

Enhancing the blue phosphorescence of iridium complexes with a dicyclometalated phosphite ligand via aza-substitution: a density functional theory investigation

2014 ◽  
Vol 2 (39) ◽  
pp. 8364-8372 ◽  
Author(s):  
Gahungu Godefroid ◽  
Liu Yuqi ◽  
Si Yanling ◽  
Su Juanjuan ◽  
Qu Xiaochun ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Photophysical Properties ◽  
Iridium Complexes ◽  
Chemical Methods ◽  
Functional Theory ◽  
Quantum Chemical Methods ◽  
Blue Phosphorescent

The influence of azasubstitution on electronic and photophysical properties of iridium complexes of blue phosphorescent dicyclometalated phosphite has been explored using quantum chemical methods.

scholarly journals Sulfate radical oxidation of aromatic contaminants: a detailed assessment of density functional theory and high-level quantum chemical methods

2017 ◽  
Vol 19 (3) ◽  
pp. 395-404 ◽  
Author(s):  
Sangavi Pari ◽  
Inger A. Wang ◽  
Haizhou Liu ◽  
Bryan M. Wong
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Sulfate Radical ◽  
Chemical Methods ◽  
Functional Theory ◽  
Radical Oxidation ◽  
Quantum Chemical Methods ◽  
Detailed Assessment ◽  
High Level

DFT and high-level quantum methods are utilized to explore sulfate radical-driven oxidation.

SPECTROSCOPIC AND QUANTUM-CHEMICAL INVESTIGATION OF TESTOSTERONE PROPIONATE, A COMMONLY MISUSED ANABOLIC STEROID

2021 ◽  
Author(s):  
Nikola Ristivojević ◽  
◽  
Dušan Dimić ◽  
Marko Đošić ◽  
Stefan Mišić ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Testosterone Propionate ◽  
Anabolic Steroids ◽  
Chemical Methods ◽  
Dft Methods ◽  
Functional Theory ◽  
Quantum Chemical Methods ◽  
Td Dft ◽  
Ir And Raman

Anabolic steroids are a group of commonly counterfeit substances used by individuals who want to gain weight and muscles. Testosterone propionate (TP), an ester analog of testosterone, belongs to this group and its spectroscopic analysis is important especially when it is improperly labeled and misused. In this contribution quantum chemical methods, at the B3LYP/6- 311++G(d,p) level of theory, were applied for the prediction of the vibrational (IR and Raman) and UV-VIS spectra of TP. The applicability of the chosen level of theory was proven based on the comparison between experimental and theoretical bond lengths and angles. The most prominent bands in the IR and Raman spectra were assigned and correlated with the calculated ones. The electronic spectra were also analyzed and the assignments were made based on the Time-Dependent Density Functional Theory (TD-DFT) calculations. The orbitals included in the most intense transitions were visualized and possible solvent effects were discussed. The presented results proved the applicability of the DFT methods for the prediction of spectra that could lead to the counterfeit substances determination.

scholarly journals Predicting OH stretching fundamental wavenumbers of alcohols for conformational assignment: different correction patterns for density functional and wave-function-based methods

2021 ◽  
Vol 23 (9) ◽  
pp. 5629-5643
Author(s):  
Robert Medel ◽  
Martin A. Suhm
Keyword(s):  
Wave Function ◽  
Quantum Chemical ◽  
Density Functional ◽  
Chemical Methods ◽  
Quantum Chemical Methods

Affordable predictions for absolute OH stretching fundamental wavenumbers of alcohols with conformational accuracy are possible when the different deficiencies of quantum chemical methods are empirically corrected.

scholarly journals Localized Active Space Pair-Density Functional Theory

2021 ◽  
Author(s):  
Riddhish Pandharkar ◽  
Matthew R. Hermes ◽  
Christopher J. Cramer ◽  
Donald G. Truhlar ◽  
Laura Gagliardi
Keyword(s):  
Density Functional Theory ◽  
Wave Function ◽  
Spin State ◽  
Density Functional ◽  
State Energy ◽  
Correlation Energy ◽  
Functional Theory ◽  
Active Space ◽  
Energy Gaps ◽  
Pair Density

Accurate quantum chemical methods for the prediction of spin-state energy gaps for strongly correlated systems are computationally expensive and scale poorly with the size of the system. This makes calculations for many experimentally interesting molecules impractical even with abundant computational resources. In previous work, we have shown that the localized active space (LAS) self-consistent field (SCF) method is an efficient way to obtain multi-configuration SCF wave functions of comparable quality to the corresponding complete active space (CAS) ones. To obtain quantitative results, a post-SCF method is needed to estimate the complete correlation energy. One such method is multiconfiguration pair-density functional theory (PDFT), which calculates the energy based on the density and on-top pair density obtained from a multiconfiguration wave function. In this work we introduce localized-active-space pair-density functional theory, which uses a LAS wave function for subsequent PDFT calculations. The method is tested for computing spin-state energy gaps in conjugated organic molecules and bimetallic compounds and is shown to give results within 0.05 eV of the corresponding CAS-PDFT results at a significantly lower cost.

Quantum chemical treatments of metal clusters

2010 ◽  
Vol 368 (1915) ◽  
pp. 1245-1263 ◽  
Author(s):  
Florian Weigend ◽  
Reinhart Ahlrichs
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Metal Clusters ◽  
Potential Surface ◽  
A Priori ◽  
Chemical Methods ◽  
Functional Theory ◽  
Chemical Treatments ◽  
Quantum Chemical Methods ◽  
Different Types

This work focuses on finding and rationalizing the building principles of clusters with approximately 300 atoms of different types of metals: main group elements (Al, Sn), alkaline earth metals (Mg), transition metals (Pd) and clusters consisting of two different elements (Ir and Pt). Two tools are inevitable for this purpose: (i) quantum chemical methods that are able to treat a given cluster with both sufficient accuracy and efficiency and (ii) algorithms that are able to systematically scan the (3 n −6)-dimensional potential surface of an n -atomic cluster for promising isomers. Currently, the only quantum chemical method that can be applied to metal clusters is density functional theory (DFT). Other methods either do not account for the multi-reference character of metal clusters or are too expensive and thus can be applied only to clusters of very few atoms, which usually is not sufficient for studying the building principles. The accuracy of DFT is not known a priori , but extrapolations to bulk values from calculated series of data show satisfying agreement with experimental data. For scans of the potential surface, simulated annealing techniques or genetic algorithms were used for the smaller clusters (approx. 20–30 atoms), and for the larger clusters considerations were restricted to selected packings and shapes. For the mixed-metallic clusters, perturbation theory turned out to be efficient and successful for finding the most promising distributions of the two atom types at the different sites.

scholarly journals Localized Active Space Pair-Density Functional Theory

2021 ◽  
Author(s):  
Riddhish Pandharkar ◽  
Matthew R. Hermes ◽  
Christopher J. Cramer ◽  
Donald G. Truhlar ◽  
Laura Gagliardi
Keyword(s):  
Density Functional Theory ◽  
Wave Function ◽  
Spin State ◽  
Density Functional ◽  
State Energy ◽  
Correlation Energy ◽  
Functional Theory ◽  
Active Space ◽  
Energy Gaps ◽  
Pair Density

Accurate quantum chemical methods for the prediction of spin-state energy gaps for strongly correlated systems are computationally expensive and scale poorly with the size of the system. This makes calculations for many experimentally interesting molecules impractical even with abundant computational resources. In previous work, we have shown that the localized active space (LAS) self-consistent field (SCF) method is an efficient way to obtain multi-configuration SCF wave functions of comparable quality to the corresponding complete active space (CAS) ones. To obtain quantitative results, a post-SCF method is needed to estimate the complete correlation energy. One such method is multiconfiguration pair-density functional theory (PDFT), which calculates the energy based on the density and on-top pair density obtained from a multiconfiguration wave function. In this work we introduce localized-active-space pair-density functional theory, which uses a LAS wave function for subsequent PDFT calculations. The method is tested for computing spin-state energy gaps in conjugated organic molecules and bimetallic compounds and is shown to give results within 0.05 eV of the corresponding CAS-PDFT results at a significantly lower cost.

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