To determine the electronic excited states and their corresponding optical properties of a molecule with a known ground state configuration using computational methods in quantum chemistry, one can follow these steps:1. Choose an appropriate quantum chemistry method: There are several computational methods available to study excited states, such as Time-Dependent Density Functional Theory TD-DFT , Configuration Interaction Singles CIS , and Coupled Cluster with Single and Double excitations CCSD . The choice of method depends on the size of the molecule, the desired accuracy, and the available computational resources.2. Perform a ground state calculation: Before studying the excited states, it is necessary to obtain the ground state electronic structure of the molecule. This can be done using methods like Hartree-Fock HF , Density Functional Theory DFT , or other correlated wavefunction methods e.g., CCSD . The ground state calculation provides the molecular orbitals and their energies, which serve as a starting point for the excited state calculations.3. Calculate the excited states: Using the chosen excited state method e.g., TD-DFT, CIS, or CCSD , calculate the excited state energies and wavefunctions. These calculations provide information about the electronic transitions between the ground and excited states, including the excitation energies and the oscillator strengths.4. Determine the optical properties: The calculated excitation energies and oscillator strengths can be used to determine the optical properties of the molecule, such as absorption and emission spectra. The excitation energies are related to the wavelengths or frequencies of the absorbed or emitted light, while the oscillator strengths give information about the intensities of the spectral lines. These properties can be compared with experimental data to validate the accuracy of the computational method and to gain insights into the electronic structure of the molecule.5. Analyze the excited state wavefunctions: The excited state wavefunctions can be further analyzed to understand the nature of the electronic transitions and their impact on the molecular geometry and properties. This can involve calculating transition densities, natural transition orbitals, or other descriptors of the excited states.In summary, determining the electronic excited states and their corresponding optical properties of a molecule using computational methods in quantum chemistry involves selecting an appropriate method, performing ground state and excited state calculations, and analyzing the resulting data to obtain insights into the electronic structure and optical properties of the molecule.