Correlation‐consistent singlet–triplet gaps in substituted carbenes

1988 ◽  
Vol 88 (3) ◽  
pp. 1752-1763 ◽  
Author(s):  
Emily A. Carter ◽  
William A. Goddard
Keyword(s):  
Correlation Consistent

scholarly journals Benchmarking the Fluxional Processes of Organometallic Piano-Stool Complexes

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2310
Author(s):  
Nathan C. Frey ◽  
Eric Van Dornshuld ◽  
Charles Edwin Webster
Keyword(s):  
Transition Metals ◽  
Density Functional ◽  
Chemical Shifts ◽  
Transition States ◽  
Electronic Energy ◽  
Basis Set ◽  
Composite Approach ◽  
Temperature Regimes ◽  
Correlation Consistent Composite Approach ◽  
Correlation Consistent

The correlation consistent Composite Approach for transition metals (ccCA-TM) and density functional theory (DFT) computations have been applied to investigate the fluxional mechanisms of cyclooctatetraene tricarbonyl chromium ((COT)Cr(CO)3) and 1,3,5,7-tetramethylcyclooctatetraene tricarbonyl chromium, molybdenum, and tungsten ((TMCOT)M(CO)3 (M = Cr, Mo, and W)) complexes. The geometries of (COT)Cr(CO)3 were fully characterized with the PBEPBE, PBE0, B3LYP, and B97-1 functionals with various basis set/ECP combinations, while all investigated (TMCOT)M(CO)3 complexes were fully characterized with the PBEPBE, PBE0, and B3LYP methods. The energetics of the fluxional dynamics of (COT)Cr(CO)3 were examined using the correlation consistent Composite Approach for transition metals (ccCA-TM) to provide reliable energy benchmarks for corresponding DFT results. The PBE0/BS1 results are in semiquantitative agreement with the ccCA-TM results. Various transition states were identified for the fluxional processes of (COT)Cr(CO)3. The PBEPBE/BS1 energetics indicate that the 1,2-shift is the lowest energy fluxional process, while the B3LYP/BS1 energetics (where BS1 = H, C, O: 6-31G(d′); M: mod-LANL2DZ(f)-ECP) indicate the 1,3-shift having a lower electronic energy of activation than the 1,2-shift by 2.9 kcal mol−1. Notably, PBE0/BS1 describes the (CO)3 rotation to be the lowest energy process, followed by the 1,3-shift. Six transition states have been identified in the fluxional processes of each of the (TMCOT)M(CO)3 complexes (except for (TMCOT)W(CO)3), two of which are 1,2-shift transition states. The lowest-energy fluxional process of each (TMCOT)M(CO)3 complex (computed with the PBE0 functional) has a ΔG‡ of 12.6, 12.8, and 13.2 kcal mol−1 for Cr, Mo, and W complexes, respectively. Good agreement was observed between the experimental and computed 1H-NMR and 13C-NMR chemical shifts for (TMCOT)Cr(CO)3 and (TMCOT)Mo(CO)3 at three different temperature regimes, with coalescence of chemically equivalent groups at higher temperatures.

Spectroscopic investigations on BH+ (X2 Σ+ ) ion using MRCI method and correlation-consistent sextuple basis set augmented with diffuse functions

2011 ◽  
Vol 111 (10) ◽  
pp. 2171-2179 ◽  
Author(s):  
De-Heng Shi ◽  
Hui Liu ◽  
Jin-Ping Zhang ◽  
Jin-Feng Sun ◽  
Yu-Fang Liu ◽  
...  
Keyword(s):  
Basis Set ◽  
Spectroscopic Investigations ◽  
Correlation Consistent

Inelastic scattering of interstellar silyl cyanide (SiH3CN) by helium atoms : cross-sections and rate coefficients for A- and E-SiH3CN

2021 ◽  
Vol 507 (4) ◽  
pp. 5264-5271
Author(s):  
Manel Naouai ◽  
Abdelhak Jrad ◽  
Ayda Badri ◽  
Faouzi Najar
Keyword(s):  
Inelastic Scattering ◽  
Total Energy ◽  
Cross Sections ◽  
Three Dimensional ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Explicitly Correlated ◽  
Correlation Consistent ◽  
Triple Excitation

ABSTRACT Rotational inelastic scattering of silyl cyanide (SiH3CN) molecule with helium (He) atoms is investigated. Three-dimensional potential energy surface (3D-PES) for the SiH3CN–He interacting system is carried out. The ab initio 3D-PES is computed using explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation CCSD(T)-F12a connected to augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. A global minimum at (R = 6.35 bohr; θ = 90○; ϕ = 60○) with a well depth of 52.99 cm−1 is pointed out. Inelastic rotational cross-sections are emphasized for the 22 first rotational levels for total energy up to 500 cm−1 via close coupling (CC) approach in the case of A-SiH3CN and for the 24 first rotational levels for total energy up to 100 cm−1 via CC and from 100 to 500 cm−1 via coupled states (CS) in the case of E-SiH3CN. Rate coefficients are derived for temperature until 80 K for both A- and E-SiH3CN–He systems. Propensity rules are obtained for |ΔJ| = 2 processes with broken parity for A-SiH3CN and for |ΔJ| = 2 processes with |ΔK| = 0 and unbroken parity for E-SiH3CN.

scholarly journals Application of the Correlation Consistent Composite Approach (ccCA) to Third-Row (Ga−Kr) Molecules

2008 ◽  
Vol 4 (2) ◽  
pp. 328-334 ◽  
Author(s):  
Nathan J. DeYonker ◽  
Benjamin Mintz ◽  
Thomas R. Cundari ◽  
Angela K. Wilson
Keyword(s):  
Composite Approach ◽  
Correlation Consistent Composite Approach ◽  
Correlation Consistent

scholarly journals Spectroscopic constants and anharmonic force field of dithioformic acid and its isomers: a theoretical study

2021 ◽  
Author(s):  
Weixiu Pang ◽  
Xiaomin Song ◽  
Yunbin Sun ◽  
Meishan Wang
Keyword(s):  
Force Field ◽  
Dipole Moments ◽  
Molecular Structures ◽  
Basis Sets ◽  
Astronomical Observation ◽  
Spectroscopic Constants ◽  
Fundamental Frequencies ◽  
Correlation Consistent ◽  
Consistent Basis ◽  
Anharmonic Force

Abstract The potential astronomical interest dithioformic acid (trans-HC(=S)SH) exists five isomers and has received considerable attention of astronomical observation in recent years. The different positions of H atoms of five isomers lead to diverse point groups, dipole moments, and spectroscopic constants. The anharmonic force field and spectroscopic constants of them are calculated using CCSD(T) and B3LYP employing correlation consistent basis sets. Molecular structures, dipole moments, rotational constants, and fundamental frequencies of trans-HC(=S)SH are compared with the available experimental data. The B3LYP/Gen=5 and CCSD(T)/Gen=Q results can reproduce them well. Molecular structures, dipole moments, relative energies, spectroscopic constants of cis-HC(=S)SH and dithiohydroxy carbene (DTHC) are also calculated. The new data obtained in this study are expected to guide the future high resolution experimental work and to assist astronomical search for CH2S2.

Adaptive Behavior and Intelligence in Adolescents With Down Syndrome: An Exploratory Investigation

2019 ◽  
Vol 57 (2) ◽  
pp. 79-94 ◽  
Author(s):  
Camila Sabat ◽  
Marc Tassé ◽  
Marcela Tenorio
Keyword(s):  
Down Syndrome ◽  
Adaptive Behavior ◽  
Intellectual Functioning ◽  
Practical Skills ◽  
Relationship Patterns ◽  
Exploratory Investigation ◽  
Correlation Consistent ◽  
Relationship Of ◽  
The Relationship ◽  
Medium Correlation

Abstract Down syndrome (DS) is characterized by difficulties in both intellectual functioning and adaptive behavior. These sets of abilities are considered as separate but related domains with small to moderate correlations. The main objective of this study was to explore the relationship of intellectual functioning and adaptive behavior in adolescents with DS because previous studies have shown different relationship patterns between these constructs across other syndromes. Fifty-three adolescents with DS were assessed regarding their intellectual functioning whereas adaptive behavior was reported by parents and teachers. Participants showed a better performance on verbal than nonverbal tasks when assessing intellectual functioning, contrary to previous findings. Regarding adaptive behavior, higher social skills were reported than conceptual and practical skills. Intellectual functioning and adaptive behavior showed a medium correlation, consistent with observations in typical population. These results support the exploration of the variability across the DS phenotype.

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