The conductance of a molecule can change significantly when different functional groups are attached to it. According to density functional theory DFT calculations of electronic transport properties, the change in conductance depends on several factors, including the nature of the functional groups, their position on the molecule, and the molecular orbitals involved in the electron transport process.1. Nature of the functional groups: Functional groups with different electron-donating or electron-withdrawing properties can alter the electronic structure of the molecule. For example, electron-donating groups can increase the electron density in the molecule, potentially leading to higher conductance. In contrast, electron-withdrawing groups can decrease the electron density, resulting in lower conductance.2. Position of the functional groups: The position of the functional groups on the molecule can also affect the conductance. If the functional group is attached to a part of the molecule that is directly involved in the electron transport pathway, it can have a more significant impact on the conductance compared to when it is attached to a less critical part of the molecule.3. Molecular orbitals: The conductance of a molecule depends on the alignment of its molecular orbitals with the energy levels of the electrodes in the electronic transport setup. Attaching functional groups can change the energy levels and the spatial distribution of the molecular orbitals, which in turn can affect the conductance.DFT calculations can provide valuable insights into the electronic structure and transport properties of molecules with different functional groups. By analyzing the changes in the molecular orbitals, energy levels, and electron density, researchers can predict how the conductance of a molecule will be affected by the attachment of various functional groups. This information can be useful for designing molecules with specific electronic properties for applications in molecular electronics and other fields.