Hey there Smrutiranjan Mekap! Now, when you Smrutiranjan Mekap stumble upon more Raman modes than you Smrutiranjan Mekap were expecting for a crystal structure, that's like finding extra toppings on your pizza – unexpected, but sometimes delightful. In the world of crystallography, this could be due to a few reasons.

First off, crystal imperfections can throw a party for extra vibrational modes. Dislocations, vacancies, or even impurities can contribute to the symphony of Raman peaks. It's like the crystal's way of saying, "Hey, I've got a few surprises up my lattice!"

Also, consider symmetry breaking. If your crystal structure is not as pristine and symmetric as you Smrutiranjan Mekap thought, it might lead to additional modes popping up, like unexpected guests crashing the party. Symmetry is crucial in crystallography, and when it's compromised, things can get a bit jazzy.

Experimental factors can also be the culprit. Sometimes, equipment sensitivity or resolution might unveil modes that were hiding in the noise before. It's like upgrading your glasses – suddenly, you see things you never noticed.

In a nutshell, when you've got more Raman modes than expected, it's time to play detective. Check for crystal defects, symmetry issues, and don't forget to scrutinize your experimental setup. It's all part of the fun in the fascinating world of crystallography!

When molecules are Raman active, you would expect vibrational modes in the spectral due to the various bonds and functional groups that make up these molecules. But additionally, you would expect or see modes due to the entire molecule vibrating as a single 'unit', this is usually referred to as 'phonon mode' vibrations.