 Can you hear me now? Can you hear me now? Not audible? Yes, sir, I can hear you. Okay, great. But people are still writing in the chat box that's not audible. That will be there. Audible. Okay, great. Okay. All right. So, and you can also see my screen, right? So welcome everyone to the first live session of symmetry and group theory course. And I will be waiting for your questions so that we can start the discussion here. So please start shooting your questions. So I hope you guys are having fun with the course. So as you see that it is basically visualizing the symmetry of the molecules. Then in the later part of the course, we will see how to group those molecules based on symmetry. And finally, we'll see how to apply those that grouping to solve some physical chemistry problems. So so far, it's only looking at symmetry of molecules and how to arrange those molecules or how to group those molecules in symmetry. So please start asking questions so that we can make good use of the session. So this is a doubt clearing session. So unless you have any questions, I won't be able to. This is not a teaching session. Okay. So first question is, can you please discuss hydrogen atom symmetry on the basis of group theory. So, when you talk about atoms. So this is a spherically symmetric molecule, right? So this is a spherically symmetric atom, I would say. So in this case, the point group, we have not. So this course does not cover the molecules containing spherical atoms. So hydrogen atom, that's why we will we have not discussed and will not be discussing but just to tell you it belongs to our three point group, which is a spherically symmetric and it has all this is a maximum symmetric point group and it has all the symmetry elements, which you can imagine, right? So it is, of course, because it's a spherically symmetric thing. So you can imagine all sorts of planes, I or all sorts of rotation, everything is possible in this. So it's the highest symmetric point group, which is our three. But we will not be discussing because it doesn't concern us as far as the physical properties of the molecules are concerned. We will give a, we'll talk about it briefly when we will talk the MO theory at that time or maybe crystal field theory. So at that time, we will discuss it briefly, but not a lot. Excuse me, sir. So C2 and CN. So what is the difference you want to ask, right? Between C2 and CN. So this question is by Navdeep Sharma. So C2 and CN. So C2 is, for example, if you have C2, so the rotation here is pi 2 pi by the order of the principal axis, which is two here. So this is 180 degree. And CN is any general principal, any general rotation axis where the rotation is given by 2 pi by N. So this is the rotation angle. So CN is a general rotation axis and C2 is a specific rotation axis where the rotation angle is defined. In CN, the rotation angle is not defined. I hope it makes sense. So again, monster group will not be, will be out of scope of this symmetry and group theory course. So let us not go there. Because then I'll have to introduce a lot of other things to do. So Saurav is asking is the CH4 has eye center. No, CH4 does not have eye center. So CH4 is drawn like this. This is your CH4. So if it has to have eye center, let us assume that it has an eye at carbon. So if you draw a line from this hydrogen atom towards carbon and then you draw, extend that line, it should find another hydrogen atom, which it does not. So no center of symmetry in CH4. Does that make sense? Any other doubt? So I see in the discussion forum, you guys are having a lot of questions and if something is not clear, we can discuss here. I have tried to answer most of the questions there, but if there is anything which is not still not clear, we can discuss over here. So group multiplication. So what do you, can you please be specific about what do you want to ask about group multiplication? Okay. So I can tell a little bit what I understand from that question. So, so let us say if I have C2 v point group if we are talking about and the point, the symmetry elements or the symmetry operations are C2, sigma v1 and sigma v2. Or we can write in terms of x's also. So we can write instead of this, we can say this will be xz and yz, right? So similarly here if we write C2z, sigma vxz, sigma vyz, then you take this element and take this element and write it here. Okay. Similarly here, e comes from here C2z comes from here. So this is how you write the group multiplication table. Okay. Now, what happens after you do this multiplication? So for that, what you have to do is for example, if I write this element, this will be C2z and sigma vxz. So let us take the example of water molecule. So in this, if you apply sigma xz first, so whatever comes, you write that and then on to this, you apply C2z. Okay. And then whatever is the resultant, you write that. Now from here to here, which symmetry operation will directly give you this confirmation that comes as a result of this multiplication. Okay. So that is what is meant by group multiplication table. So you have to fill in all the spots here by doing these operations. I hope this is what you were asking. And so for net exam, Cotton and Carter are two books which generally cover most of the stuff which is asked in net. But I'm not sure because I have not looked at the net question paper for last few years. So what is the trend now but course wise, Cotton and Carter would cover most of the stuff. So relation between a Lie group and a Lie algebra. So again, this is going into mathematics. So we'll not, this is out of the course scope of this course. So we will not be going in that direction. Symmetry element present in distorted octahedron in which three cis angle cis 90 degrees were closed. Okay. So for books, it is Cotton and second book is by Carter. Okay. So distorted octahedron in which three cis 90 degree angles were closed. So let us try to see what you're saying. So if I have a distorted, if I have a regular octahedron, I can draw it like this where the atoms are at this axis and the central atom is here. Now these, these are the three cis angles between x, y and z, which are otherwise 90 degree in a regular octahedron. So this is a regular octahedron. Now if we distort this by bringing these two, these three angles closer, so that means x, y and z would behave something like this. So if I'm looking from the side, it looks something like this, right. So I have over exaggerated this closing. So let's say this is x, y and z. Similarly, the other side of this will be minus x, minus y, minus z. Okay. Right. So now if you see what will be the, this will be like a staggered ethane molecule. So I hope you can find out what is the point group of this now, right. We have discussed staggered ethane molecule in this. Let me know if that is clear. So thank you, Brian. So this course is about the application of symmetry and group theory to solving physical chemistry problems. Okay. So this is not mathematically very rigorous in the sense that we will not be using all the properties of group theory. We'll be using only selected properties of group theory which are, which are relevant in terms of solving physical chemistry problems. I hope that helps. Any more doubts? Any questions? Sure. You're welcome. So physical significance of subgroups will come at a later stage when we will, when we will see the correlation tables. So we will see that later. Actually, right now you are at only fourth or fifth week, right. So we will see that towards eighth or ninth week, it will come. So thank you, honey, but this is online course, black board teaching and due to Corona virus. The physical teaching is not possible. So that's why it is writing on electronic media. So I'm sorry if that is not giving you the feeling. So this is first time I'm doing electronic board teaching. So maybe, but I hope the content is okay and engaging. So I hope you all have gone through the videos which are, which have been broadcasted till now. So please ask questions overlap with condensed matter solid state physics. No Brian, there would not be any overlap with condensed matter or solid state physics. Because we are only discussing here discrete group theory and that too very limited with which is applicable for chemical applications in particular physical chemistry. So solid state physics will not be overlapping with this. Any more doubts? You probably can see the desktop itself because I have not put up anything on the screen as of now. That's why I will you can't see the screen because there is no question. So I'm looking at the chat window right now so that I can answer if there are any questions. No roman tensors in this course. No, Shahid, we will not be discussing roman tensors here. So formal name of the courses symmetry and group theory. Any more doubts. So next interaction session will be next month. So please raise if you have any doubts. Shivani we started around 20 minutes back. But you may ask if you have any doubts. So applications of group theory are discussed later in the later part of this course. So we will be discussing will be covering in the later video. So right now it's only the symmetry part which is going on where the how to find out symmetry apply symmetry elements and symmetry operations and grouping molecules based on that is going on this week. So later part of this course will cover hybridization application of group theory. So let us keep that question for maybe second interaction session next month. So shake the books I have mentioned earlier are cotton and another book is by Carter. If you just search group theory cotton group theory Carter you will see all the details of this. These two books. Doubts please. Any more questions. That should work. So the difference between different books is that sometimes the how they put the or how they orient the molecule in the coordinate system is can be a little different and how the how they rotate molecules in different symmetry operations can also be different. Some books follow clockwise some books follow anti clockwise but but if you are following one book for a particular problem it should not be an issue. Yes, I'm sure NPTEL office will provide you the recording. So less number of questions means the teaching is going very good. Right. So I can give a pat on my back. Actually there can be two things either it is going very good or it is going all in the air. So no more doubts. So it says 49 people watching right now. And there is no doubt. Right. No, this is just to thank you Brian so I'm just making sure that there is no hesitation in asking questions. Please do not be inhibited for asking questions. As long as it is relevant for this course I will answer those questions. The question is specifically for solving doubts. So please do not be inhibited please do ask doubts if you have. So no doubts it seems. Okay. So that means all the students are learning very nicely and I'm teaching very nicely. Both of this. All right so if there are no questions so please do post on the discussion forum if there are any questions and I will answer there and then we will have an again this interaction session next month. So if you can pile up all your questions we can discuss unless you want to clarify it in the forum. We can discuss here. All right. So if there are no questions, probably we can stop. Thank you sir I will stop the live now. Thanks for the session. Was great interacting with all of you.