• Optimize the following structure with B3LYP/ 6-31+G(d). Notice that different electron spin multiplicity might cause different structures, compare the energies too.

step

1. Guess a possible structure and draw it with spartan'20.
2. Build files using optimized instructions singlet and triplet.
3. Useing Guassian 16 executive file .

1.singlet   energy=-2941.32293 hartree                                                   2.triplet    energy=-2941.33094 hartree           

• Plot the eletron density of He and He- and use MP2 theory with d-aug-cc-pVTZ and aug-cc-pVTZ  basis sets.

1. Create a <.com> file
2. Execute <.com> to generate <.chk> file
3. Use the <formchk> command to form a <.fchk> file
4. Create a <xyz.dat> file and use <cubegen> to generate a <.cube> file
5. Extract data from <.cube> files and make graphs
6. As shown below

7.結果

Figure 1

Figure 2

Figure 3

8.結論

<1>adding an additional diffuse function can reduce the error in EA calculation of noble gas .From the Figure 1 (R*R*Density), you can see that adding diffuse funtion can better describe the calculated molecule.