DFT molecular structure relaxation of the ethanol,
Perform a DFT molecular structure relaxation of the ethanol, C2H5OH. Use the def2-TZVP basis set using spin restricted and spin unrestricted methods. Use resolution of identity (RI/JK, or autoaux) options for enabling the density fitting of bielectronic integrals and speedup the calculation.
Questions & tasks:
Search in the output the following quantities and show the comparison. Make a table showing these quantities for the two calculations:
a) Mulliken and Lowdin atomic charges on the O, C, H atoms
b) Vibrational frequencies
c) Electric dipole moment
d) Determine HOMO-LUMO gap for the optimized structure. Use AVOGADRO or CHEMCRAFT to plot the HOMO, HOMO-1, and HOMO-2, LUMO, LUMO-1, and LUMO-2 molecular orbitals.
e) Plot the total electronic density
f) Plot the total electrostatic potential of the molecule
f) How do you confirm that the relaxed structure corresponds to the minimum on the potential energy surface (PES)? What is the dimensionality of the PES for this molecule (i.e. how many degrees of freedom are there)?
Exercise 2:
Consider the O2 molecule for the distance is R=1.208 Angstrom. You will use CASSCF methods and ANO-RCC-VTZP basis sets to calculate the ground energy state for the cases when total spin is S=0, S=1 and S=2. Consider the two versions of the active space of the CASSCF method:
1) CAS(8 in 6), i.e. eight electrons spanning six valence orbitals (π-orbitals of each O atom).
2) CAS(12 in 8), i.e. include the 2s shells of O atoms in the active space. This means that the active space (1) is expanded to include the two molecular orbitals made by the 2s2 shells of each O atom.
Questions & tasks:
a) Refresh the knowledge about the molecular orbital diagram of the O2 molecule. Search for it in the literature. Inspect the ground state configuration. What is the ground state spin of O2 molecule?
b) How many roots (states) do you have in total for wave functions with total spin S=0, S=1 and S=2 for each of the provided size of the active space? Hint: you may use the Weyl’s formula to compute this number. For each spin value mention the degeneracy (multiplicity) of the ground state? As example, the ground state for S=1 is non-degenerate. What about the S=0 and S=2 cases?
c) Calculate the ground state total energies for each of these spin states using the above O-O distance (6 values). If the ground state is degenerate for the particular value of the spin, then use the state-average CASSCF method.
d) Optimize the molecular structure for each of the above 6 cases and evaluate the vibrational frequency for each case.
2) Include the NEVPT2 option and perform the optimization of the molecular structure for each of the above 6 cases and evaluate the vibrational frequency for each case.
How does the size of the active space influence the optimal bond distance in O2 molecule?
How does the ground state spin influence the optimal bond distance in O2 molecule?
How does the dynamical correlation (NEVPT2) influence the optimal bond distance in O2 molecule and vibrational frequency?
Discuss briefly about the obtained results.
Sandra, a 47-year-old divorced woman, received a diagnosis of stage 3 ovarian cancer 4 years ago, for which she had a total hysterectomy, bilateral salpingo- oophorectomy, omentectomy, lymphadenectomy, and tumor debulking followed by chemotherapy, consisting of cisplatin (Platinol), paclitaxel (Taxol), and doxorubicin (Adriamycin). She did well for 2 years and then moved back to her hometown near her family and underwent three more rounds of secondline chemotherapy. She accepted a less stressful job, bought a house, renewed old friendships, and became more involved with her two sisters and their families.
Sandra developed several complications, including metastasis to the lungs. Then she could no longer work, drive, or care for herself. She had been told by her oncologist that there was nothing else that could be done and that she should consider entering a hospice. She met her attorney and prepared an advance directive and completed her will. She decided to have hospice care at home and, with the help of her family, set up her first floor as a living and sleeping area. She was cared for by family members around the clock for approximately 3 days.
Sandra observed that she was tiring everyone out so much that they could not really enjoy each other’s company. At this time, she contacted the Visiting Nurse Association (VNA) to seek assistance. Her plan was to try to enjoy her family and friend’s visits. After assessment, the VNA nurse prioritized her problems to include fatigue and caregiver role strain. Other potential problem areas that may need to be incorporated into the care plan include anticipatory grieving and impaired comfort.
Reflective Questions
- What are some of the stresses on Sandra’s middle-aged sisters and their families?
- What resources are available to manage these stresses and support the sisters while caring for their dying sister Sandra?
- Describe Sandra’s feelings about dependency and loss of autonomy because she is unable to do her own activities of daily living any longer
