Computational Chemistry

(b) Actinides and relativistic core potentials (pseudopotentials). Odoh SO, Schreckenbach G,

J Phys Chem A, (2010), 114:1957

Solvation.....................................................................

Easier Questions..........................................................

Easier Questions..........................................................

1. Using microsolvation, roughly how many water molecules might be needed to
   provide one layer around CH 3 F (suggestion: examine space-filling hand-held or
   computer-generated models)?


2. What physical properties of solvents have been used to parameterize them for
   continuum calculations?


3. Give an example of a reaction for which just one explicit solvent molecule might
   be adequate in simulating a reaction mechanism.


4. For continuum solvation, give an example of a molecule for which a good
   approximation might be (a) a spherical cavity, (b) an ellipsoidal cavity.


5. Why are continuum solvation methods more widely used than microsolvation
   methods?

Harder Questions.........................................................

1. In microsolvation, should thesolvent molecules be subjected to geometry
   optimization?


2. Consider the possibility of microsolvation computations with spherical, polar-
   izable “pseudomolecules”. What might be the advantages and disadvantages of
   this simplified geometry?


3. In microsolvation, why might just one solvent layer be inadequate?


4. Why is parameterizing a continuum solvent model with the conventional dielec-
   tric constant possibly physically unrealistic?


5. Consider the possibility of parameterizing a continuum solvent model with
   dipole moment.

Singlet Diradicals............................................................

Easier Questions

1. A monoradical is a doublet and a diradical can be a singlet or a triplet. How
   many spin states are possible for a triradical?


2. What does the Pauli exclusion principle suggest about the relative energies of
   singlet and triplet diradicals?

558 8 Some “Special” Topics