Recent content by greisen

it is in gas phase

Hi all, I am using Koopmans theorem trying to estimate excitation energy so I have calculated the homo/lumo for molecule A as well as for A- and A+(adding and removing an electron respectively). Then I would use the formula Egap = min[(E(n+1)-E(n)]-[E(n)-E(n-1)]] I get a energy gap...

Hi, I have to show that if the derivate f'(x) of a generalized function f(x) is defined by the sequence f'_n(x) where f(x) is defined f_n(x)[\tex] then \int_{-\infty}^{\infty}f'(x)F(x) dx = - \int_{-\infty}^{\infty}f(x)F'(x) dx I use the limits for generalized functions and...

Hi, I have to write the 1/(a+ib) as a sum of a real part and an imaginary part. I was thinking of using the complex conjugate (a-ib) and multiply with this (a-ib) / (a^2 + b^2) I am a little bit lost on what to do next - any help appreciated thanks in advance Best

Thanks yes I have tried integration by parts but that got very messy. I don't quite understand how to rewrite the equation involving the anti-derivative?

Hi, I have to find a general formula for the function 1/(2n)!\int_{-\inf}^{\inf}x^{2n}*e^{-ax^2} I am a little bit lost in how to proceed - any hints appreciated thanks in advance

if you write up Heisenbergs uncertainty principle and plug in the numbers from the exercise you should see that the uncertainty principle is not so relevant for the bacteria. Try to write up the equation and put in the numbers...

I can see that some of the exponents have vanished so the integral which gives me problems is - \int dr^{3} dr'^{3} \frac{n^{2}}{|r-r'|} which in scaled coordinates can be written as - \frac{3}{4*pi}\int d\tilde{r}^{3} \frac{1}{\tilde{r}}

just to ask - when would a mean field approximation fail? Non-adiabatic processes?

Hi, So if I transform and the volume of the transform is preserved the size of |J| is one?

Hi, I am using the book "Advanced Engineering Mathematics" by Erwin Kreyszig where I am reading on the transformation of coordinates - when changing from \int f(x,y) to \int f(v(x,y),v(x,y) it is necessary to multiply with the size of the jacobian, |J| - I cannot find the proof in the book...

I have to show that the hamiltonian for a homogeneous system can be simplified in scaled coordinates. The first two terms I can convert to scaled coordinates <T>+<V> whereas I have some trouble for the last term -½* \int d³r d³r' \frac{n²}{|r-r'|} where n is the density. The scaled...

Yes - that is my question. I would presume that in a QM/MM one would converge to structure when the QM part would converge due to some gradient tolerance but I am not quite sure about the QM/MD. Any advise appreciated - thanks

Hi all, I have a general questions on which is the difference between these two methods QM/MM and QM/MD? Any hints appreciated - thanks in advance Best

Hi, I have to convert my force constant from N/m to kcal/(mol*m^2) but I don't know where to start. Any help appreciated. Thanks