1.•Please use ChatGPT to explore a thematic series of questions within the scope of computational chemistry and follow up with further inquiries about any unfamiliar terms  ( except homework )

2.•Calculate the first 13 excitation energy of Hydrogen(from 1s to 2s, 2p, 3s, 3p and 3d orbitals) atom by using the CIS theoretical method with appropriate basis sets ( need to include diffuse functions or other elements ) then compare with the experimental values.

Exp value of the two lowest excitation energy(n=1>n=2 and n=1>n=3) of Hydrogen are 10.2, 12.1eV.(from class material)

Table1. Total error of the first 13 singlet excited states with their exp values calculated by CIS method.

3.Calculate the first 5  excitation energy of Helium( from 1s to 2s, 2p and 3s) by using the CIS、CIS(D) theoretical method with appropriate basis sets then compare with the experimental values.

Exp value of the two lowest excitation energy(1s12s1, 1s12p1 and 1s13s1) of Helium are 20.6, 21.2, 22.9eV.

(from class material and

Table 2. Sum of the error bwtween the first 4 singlet excited states and thier exp values calculated by CIS method.(Unit: eV)

Table 3. Sum of the error between the first 4 singlet excited states with thier exp values calculated by CIS(D) method.(Unit: eV)