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51.
Pressure-induced phase transition and structural behavior of MgO at high temperatures: a model study
A realistic interaction potential model approach by including temperature effects is developed to study phase transition, elastic properties and thermo-physical properties at very high pressures and temperatures. This approach is effectively able to explain the inter-atomic interaction involved at high temperature and high pressure as it includes the three-body interactions. Earlier works overlooked the three-body interactions at high temperature and pressures. Moreover, the phase-transition pressures of MgO crystal at high temperatures including the three-body interaction are computed for the first time. Elastic behavior, anisotropic factor and Debye temperature of MgO at high pressures and temperatures are also reported. 相似文献
52.
In the present paper, we have investigated the static properties of the mixed ionic crystal NH4Cl1−x
Br
x
using three-body potential model (TBPM) by the application of Vegard’s law. The results for the mixed crystal counterparts
are also in fair agreement with the pseudo-experimental data generated from the application of Vegard’s law. The results for
the end point members (x = 0 and 1) are in good agreement with the experimental data. The results on compressibility, molecular force constant, infrared
absorption frequencies and Debye temperature are presented probably for the first time for these mixed crystal counterparts. 相似文献
53.
The problem of center-of-mass (CM) contaminations in ab initio nuclear structure calculations using configuration interaction (CI) and coupled-cluster (CC) approaches is analyzed. A rigorous and quantitative scheme for diagnosing the CM contamination of intrinsic observables is proposed and applied to ground-state calculations for 4He and 16O. The CI and CC calculations for 16O based on model spaces defined via a truncation of the single-particle basis lead to sizable CM contaminations, while the importance-truncated no-core shell model based on the NmaxΩ space is virtually free of CM contaminations. 相似文献
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Ge Y Gordon MS Piecuch P Włoch M Gour JR 《The journal of physical chemistry. A》2008,112(46):11873-11884
The recently developed restricted open-shell, size extensive, left eigenstate, completely renormalized (CR), coupled-cluster (CC) singles (S), doubles (D), and noniterative triples (T) approach, termed CR-CC(2,3) and abbreviated in this paper as ROCCL, is compared with the unrestricted CCSD(T) [UCCSD(T)] and multireference second-order perturbation theory (MRMP2) methods to assess the accuracy of the calculated potential energy surfaces (PESs) of eight single bond-breaking reactions of open-shell species that consist of C, H, Si, and Cl; these types of reactions are interesting because they account for part of the gas-phase chemistry in the silicon carbide chemical vapor deposition. The full configuration interaction (FCI) and multireference configuration interaction with Davidson quadruples correction [MRCI(Q)] methods are used as benchmark methods to evaluate the accuracy of the ROCCL, UCCSD(T), and MRMP2 PESs. The ROCCL PESs are found to be in reasonable agreement with the corresponding FCI or MRCI(Q) PESs in the entire region R = 1-3Re for all of the studied bond-breaking reactions. The ROCCL PESs have smaller nonparallelity error (NPE) than the UCCSD(T) ones and are comparable to those obtained with MRMP2. Both the ROCCL and UCCSD(T) PESs have significantly smaller reaction energy errors (REE) than the MRMP2 ones. Finally, an efficient strategy is proposed to estimate the ROCCL/cc-pVTZ PESs using an additivity approximation for basis set effects and correlation corrections. 相似文献
58.
Anil Malik Dr. Nand Kishor Gour Sakshi Bhatt Prof. Dr. Ramesh Chandra Deka Dr. Suman L. Jain 《European journal of organic chemistry》2023,26(11):e202201338
The synthesis of 2-oxazolidinones from a three component coupling reaction of amines, epoxides, and CO2. The reaction proceeds in the presence of 1,1,3,3-tetramethylguanidine under visible light irradiation at atmospheric pressure. The optimized structures of all species involved in the reaction mechanism along with transition states have been described based on the DFT calculations. The developed methodology represents a promising approach of employing CO2 as a naturally abundant and non-toxic carbon resource to produce profitable chemicals. 相似文献
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Kritika Gour Gargi Kundu Soumya Ranjan Dash Dr. Kumar Vanka Dr. Srinu Tothadi Dr. Sakya S. Sen 《欧洲无机化学杂志》2023,26(21):e202300167
This paper describes the rare use of a 6-membered saturated N-heterocyclic carbene (NHC) known as 1,3-di(2,6-diisopropylphenyl) tetrahydropyrimidine-2-ylidene (abbreviated as 6-SIDipp) as a ligand in zinc chemistry. We report on the investigation of the reactions between 6-SIDipp and ZnX2, which resulted in a range of new monomeric 6-SIDipp⋅ZnX2 complexes (X=Et ( 1 ), Cl ( 2 ), Br ( 3 ), and I ( 4 )). We also prepared a new NHC zinc complex where the two substituents of the zinc atom are different, 6-SIDipp⋅Zn(Et)Br ( 7 ) through the reaction of the proligand [6-SIDippH]Br with ZnEt2. We have observed that the reactions of complex 1 with sulfur and HBpin led to the removal of the ZnEt2 moiety, resulting in the formation of a C=S double bond and a B−H activation product, respectively. Lastly, the reaction of 1 with five-membered NHCs led to the exchange of carbene and the formation of either 5-IDipp⋅ZnEt2 ( 8 ) or 5-SIDipp⋅ZnEt2 ( 9 ). 相似文献
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Rohit Kumar Sandeep Yadav Kritika Gour Ekta Sangtani Soumya Ranjan Dash Abhishekram Raja Kumar Vanka Rajesh G. Gonnade Sakya S. Sen 《化学:亚洲杂志》2020,15(6):820-827
In this paper, we have used two N,O‐ketiminato ligands ( L1 and L2 ) with biphenyl and terphenyl substituent on the nitrogen atom. Deprotonation of L1 with KN(SiMe3)2 and subsequent reaction with MgI2 led to a homoleptic dinuclear magnesium complex ( 1 ) with a Mg2O2 four‐membered ring. Deprotonation with nBuLi and subsequent reaction with MgI2 afforded a unusual dinuclear magnesium complex ( 2 ) with a Mg2O2 ring. Extension of the ligand for calcium resulted in a trinuclear calcium complex ( 3 ) with six four‐membered Ca2O2 rings. We could not isolate any chelating complex when L2 was used as a ligand, and only oxygen bound magnesium ( 4 ) and calcium ( 5 ) adducts were isolated. DFT studies were performed to understand this dissimilar behavior. More diverse results were obtained when lithiated L1 and L2 were treated with germanium dichloride. We were able to stabilize a monomeric germylene monochloride ( 7 ) with L1 . However, with L2 , an unusual ligand scrambling, and a C?C coupling take place, leading to the formation of a secondary carbocation with GeCl3‐ as a counter‐anion ( 8 ). Besides, a germanium dichloride adduct ( 9 ) bound to the oxygen center of the ligand was obtained as the minor product. 相似文献