In experimental, the bond energy per atom rises quadratically with the number of bonds then why in simulations this bond energy per atom rises linearly with the number of bonds per atoms?
Sushanta Sethi From textbooks, I recalled that bond energy for carbon-carbon bonding increases roughly linearly. Online, I found for example , where it stated that single, double, and triple bonded Carbon-Carbon has 345, 611, and 837 kJ/mol, respectively. You can fit that to an equation of [Bond Energy] = 246*[number of bonds] + 105.67. So the experimental results are showing linear results as well.