研究目的
To study the electronic and electrical properties of the C60F18 polar molecule, including its electric dipole moment, distributions of electrostatic potential, electric-field strength, and electron density, for describing its adsorption and self-assembly on the Au(111) surface.
研究成果
The refined electric dipole moment of C60F18 is 10-11 D. The distributions of electrostatic potential and electric-field strength are anisotropic inside the molecule and isotropic beyond, with the point dipole approximation valid at distances twice the molecule size with 30% accuracy. DFT-calculated molecular orbitals correlate with STM images, confirming weak interactions with the Au(111) surface and the suitability of DFT for describing the electronic structure.
研究不足
The DFT approximations may have limitations in accuracy for electronic structure calculations; the point dipole approximation is only valid at distances much greater than the molecule size, with 30% accuracy at twice the size. The absence of STM analog for HOMO is due to insufficient energy resolution and low electron population.
1：Experimental Design and Method Selection:
Quantum-chemical studies using density functional theory (DFT) with various basis sets (STO-3G, 6-31G, 6-31G*, 6-31++G, 6-311++G*) and the B3LYP functional to calculate electronic and electrical properties. The GAUSSIAN98 software package was used for DFT calculations, and GaussView for molecular orbital visualization.
2：Sample Selection and Data Sources:
The C60F18 molecule with geometry from experimental data [12]. Control calculations used the CH3F molecule with known dipole moment.
3：2]. Control calculations used the CH3F molecule with known dipole moment. List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Computational software (GAUSSIAN98, GaussView), basis sets for DFT.
4：Experimental Procedures and Operational Workflow:
Calculations performed for electric dipole moment, electrostatic potential, electric-field strength, and molecular orbitals. Distributions were calculated in the z=0 plane with distances from 0 to 30 ?.
5：Data Analysis Methods:
Comparison of calculated values with experimental data (e.g., CH3F dipole moment), error estimation using vector schemes, and assignment of molecular orbitals to STM/STS images.
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