1：Experimental Design and Method Selection:

The study involved the growth of 4HLPCC single crystals by slow evaporation technique and characterization using X-ray diffraction, FTIR, FT-RAMAN, UV-Vis-NIR spectroscopy, TGA/DTA, dielectric studies, and SHG efficiency measurement. Theoretical calculations were performed using DFT with B3LYP/LanL2DZ basis set.

2：Sample Selection and Data Sources:

Analytical grade 4-hydroxy L-proline and cadmium chloride were used in a 1:1 ratio for crystal growth. Data were collected from experimental measurements and theoretical computations.

3：List of Experimental Equipment and Materials:

Enraf-nonius CAD 4 X-ray diffractometer, Thermo Scientific UV-Vis-NIR spectrometer, Perkin-Elmer RX1 spectrometer, Bruker RFS-27 FT-Raman spectrometer, Perkin Elmer STA 6000 system, HIOKI 3236 LCR meter, Q-switched Nd:YAG laser.

4：Experimental Procedures and Operational Workflow:

Crystals were grown by slow evaporation, characterized by various spectroscopic and thermal techniques, and their NLO properties were evaluated.

5：Data Analysis Methods:

Data were analyzed using Gaussian 09 software for theoretical computations, and experimental data were compared with theoretical predictions.