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OB star clusters originate from parsec-scale massive molecular clumps. We aimto understand the evolution of temperature and density structures on theintermediate-scale ($\lesssim$0.1-1 pc) extended gas of massive clumps. Weperformed $\sim$0.1 pc resolution observations (SMA+APEX) of multiple molecularline tracers (e.g., CH$_{3}$CCH, H$_{2}$CS, CH$_{3}$CN, CH$_{3}$OH) which covera wide range of excitation conditions, towards a sample of eight massiveclumps. Based on various radiative transfer models, we constrain the gastemperature and density structures and establish an evolutionary picture, aidedby a spatially-dependent virial analysis and abundance ratios of multiplespecies. We determine temperature radial profiles varying between 30-200 K overa continuous scale, from the center of the clumps out to 0.3-0.4 pc radii. Theclumps' radial gas density profiles, described by radial power-laws with slopesbetween -0.6 and $\sim$-1.5, are steeper for more evolved sources, as suggestedby results based on both dust continuum, representing the bulk of the gas($\sim$10$^{4}$ cm$^{-3}$), and CH$_{3}$OH lines probing the dense gas($\gtrsim$10$^{6}$-10$^{8}$ cm$^{-3}$) regime. The density contrast between thedense gas and the bulk gas increases with evolution, and may be indicative ofspatially and temporally varying star formation efficiencies. The radialprofiles of the virial parameter show a global variation towards a sub-virialstate as the clump evolves. The line-widths decline with increasing radiusaround the central core region and increase in the outer envelope, with a slopeshallower than the case of the supersonic turbulence ($\,\propto\,$$r^{0.5}$)and the subsonic Kolmogorov scaling ($\,\propto\,$$r^{0.33}$). In the contextof clump evolution, we also find that the abundance ratios of[CCH]/[CH$_{3}$OH] and [CH$_{3}$CN]/[CH$_{3}$OH] show correlations with clump$L/M$.

The evolution of temperature and density structures of OB cluster-forming molecular clumps