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Full-Text Articles in Physical Sciences and Mathematics
Single-Reference Coupled Cluster Theory For Multi-Reference Problems, Johannes T. Margraf, Ajith Perera, Jesse J. Lutz, Rodney J. Bartlett
Single-Reference Coupled Cluster Theory For Multi-Reference Problems, Johannes T. Margraf, Ajith Perera, Jesse J. Lutz, Rodney J. Bartlett
Faculty Publications
Coupled cluster (CC) theory is widely accepted as the most accurate and generally applicable approach in quantum chemistry. CC calculations are usually performed with single Slater-determinant references, e.g., canonical Hartree-Fock (HF) wavefunctions, though any single determinant can be used. This is an attractive feature because typical CC calculations are straightforward to apply, as there is no potentially ambiguous user input required. On the other hand, there can be concern that CC approximations give unreliable results when the reference determinant provides a poor description of the system of interest, i.e., when the HF or any other single determinant ground state has …
Non-Adiabatic Energy Surfaces Of The B+H2 Systems, Lachlan T. Belcher
Non-Adiabatic Energy Surfaces Of The B+H2 Systems, Lachlan T. Belcher
Theses and Dissertations
In order to solve the dynamics of a system, the kinetic energy operator of the Hamiltonian must be diagonalized. Diagonalization requires rotation of the system into a non-adiabatic representation. This rotation is a coupling angle determined by the derivative coupling terms. Derivative coupling terms are calculated using Columbus and Brooklyn, software packages. Separation of internal dynamics characterized by Jacobi coordinates, and external dynamics characterized by a set of Euler angles and the center of mass position, requires a transformation from Cartesian coordinates to Jacobi coordinates required for subsequent dynamical calculations. Previous attempts to solve for non-adiabatic energy surfaces in this …
Use Of Quantum Mechanical Calculations To Investigate Small Silicon Carbide Clusters, Jean W. Henry
Use Of Quantum Mechanical Calculations To Investigate Small Silicon Carbide Clusters, Jean W. Henry
Theses and Dissertations
Density Functional Theory (DFT) method was employed to model silicon carbide small clusters. Comparing the DFT calculation results with experimental results that observed by using photoelectron spectroscopy (PES), DFT predicts the same structures that experiment observed. For electron affinity, DFT results are in good agreement with experimental results, the root mean square negative offset 0.1 eV found using medium size of basis set (cc-pVDZ+) calculation. DFT results for vibrational frequencies are in good agreement with experiment results; the root mean square error is 72.5 cm-1 wave number. 16 ground state structures of SimCn (m ≤ 4, …