1. Chemistry 518: MgO nanoclusters
November 24, 2018
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2. Phase 1
The Objective of this assignment is to reproduce the results from :
The authors use a HF level of theory to optimize the geometries and get energies with 6-31G*. Additionally they compare the results to HF+MP2 theory (not shown in this presentation).
November 24, 2018
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3. Mg2O2 Mg2O2 2(b)HF=-548.9231 2(a)HF=-548.9092 R(A) Cluster(a) 1.831
Cluster(b)
1.8438
November 24, 2018
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4. Mg3O3 Mg3O3 Constrained angles (3a) HF = - 823.4677
(3b_1) HF=
(3b_2) HF=
R(A)
R(A)_1
R(A)_2
Cluster(a)
1.87
Cluster(b)
1.78
1.817
November 24, 2018
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5. Mg4O4 Mg4O4 Constrained angles (4a)HF= -1098.1223
(4b_1) HF=
(4b_2) HF=
R(A)
R(A)_1
R(A)_2
Cluster(a)
1.93
Cluster(b)
1.80/1.79
1.806
November 24, 2018
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6. Mg6O6 (6b)HF= -1647.3454 R(A) R(A)_1 (constrain) Cluster(a) 1.94
Cluster(b)
1.90 and 1.98
November 24, 2018
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7. HF+MP2 comparison HF+MP2 (Recio et al.) HF+MP2 (a,b structures) Mg2O2/ /
Mg3O3 / /
Mg4O4 / /
Mg6O6 / /
November 24, 2018
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8. Compare more clusters with HF Compare HF+MP2 results
Found that the geometries were constrained! Not true optimized geometry.
Very good agreement in energies and bond lengths of constrained geometries.
To Do:
Compare more clusters with HF
Compare HF+MP2 results
Produce potential energy surfaces for MgO clusters with different coordination numbers.
Search literature for non-stoichiometric MgO clusters.
November 24, 2018
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9. Phase 2: Motivation
Use 1st principles to capture the effect of enviroment on electron density per atom.
Parameterize results into an interatomic potential for classical Non- Equilibrium Molecular Dynamics.
Enviromentally Dependent Dynamic Charge (EDD-q) Model
Embedding term
Pair-wise interaction
Columbic interaction
Most important aspect is to determine the effective charge ,q ,on an atom as a function of nearest neighbors bond length and angles.
November 24, 2018
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10. Cluster Set Choose set of clusters with different coordination Mg2O2
Level of Theory : B3LYP
Basis Set : 6-311(d)
Type of Run: Geometry Optimization and Frequency analysis
Optimized structures are compared to literature
Vibrational modes are identified as deforming paths
Collected data is Mulliken atomic charge as a function of changing variable (bond,angle,dihederal).
November 24, 2018
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11. Mg2O2 Potential Energy Scan x1: Mg-O bond x2: Mg-O-O angle
November 24, 2018
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12. Mg2O2 – Vibrational Mode : 273.63 cm-1
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13. Mg2O2 – Vibrational Mode: 666.23 cm-1
November 24, 2018
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14. Mg2O2 – Vibrational Mode: 656.82 cm-1
November 24, 2018
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15. Thank You ! Questions?
November 24, 2018
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