density changing and what is at a given point. One example is BLYP. The meta-GGA depends on electron density and curvature of electron density but it also adds either kinetic energy or the Laplacian or both. One example is TPSS when used for water. Hybrid exchange-correlation functionals take the part of the Hartree Fock exchange the rest from DFT exchange function. The part is determined by a parameter variable. One example of this function is B3LYP.
4. Water molecules in solution tend to form clusters, such as dimers (two water molecules interacting), trimers (three water molecules interacting), or larger clusters. For this problem you are to find the binding energy between water molecules in dimers and trimers. First model a single water molecule. Then model two water molecules together. You should consider modeling an H atom from one water molecule interacting with an O atom of the other water molecule. A typical O---H distance in liquid water is about X Å. The binding energy of water is the energy of the dimer minus two times the energy of a single water molecule (E dimer – 2*E water -alone). Now do the same thing with 3 water molecules. Now the binding energy will be E trimer – 3*E water -alone. Run these calculations using B3LYP/Routine and HF/Routine. How do O---H distances compare and binding energies compare between the two methods? Exchange Correlation HF B3LYP Distance Dimeter -5.522 -6.526 1.95 Trimer -13.1775 -15.4365 1.95 The binding energy for Hartree-Fock is lower than the binding energy of B3LYP. The bonding distance is the same for both methods and the dimeter and trimer.
5. The experimental bond length of CO2is 1.162 Å and CO2has an atomization energy