Recent content by ebrattr

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    Graduate Differentiation spherical coordinates

    Yes, I mean \dfrac{\partial q}{\partial \mathbf{r}} As you know if you do \dfrac{\partial}{\partial \mathbf{r}} both sides you get \dfrac{\partial q}{\partial \mathbf{r}} -\sin q = \dfrac{\hat{\mathbf{k}}}{L} . Solving for \dfrac{\partial q}{\partial \mathbf{r}} you get \dfrac{\partial...
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    Graduate Differentiation spherical coordinates

    Hi ! I'm trying to inverse a mass matrix so I need to do something like this \dfrac{q}{\partial \mathbf{r}} where \cos q = \dfrac{\mathbf{r}\cdot \hat{\mathbf{k}}}{r} However, when \mathbf{r} = \hat{\mathbf{k}} \text{ or } -\hat{\mathbf{k}} I have problems. ¿What can I do...
    • ebrattr
    • Thread
    • Coordinates Differentiation Spherical Spherical coordinates
    • Replies: 3
    • Forum: Calculus
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    Undergrad Variables and normal distributions

    Yeahhh... its cero. Thanks.
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    Undergrad Variables and normal distributions

    Hi everyone, I would like to know if this stament is true or not. I have two variables u,v both of them distributed as normal distribution with mean 0 and variance a^2. Is it true that the expected value of uv is a^2 ? Thanks
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    Graduate Why is the energy decreasing in my atom simulation?

    Thanks ! I have found the problem !, when I compute the Total energy, in the internal cycle, it is not k \neq j , it is instead k > j .
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    Graduate Why is the energy decreasing in my atom simulation?

    Suppose I have mass of 1 kg. This not real important.
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    Graduate Why is the energy decreasing in my atom simulation?

    Mass. Magnitude of the force due to Lennard Jones potential.
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    Graduate Why is the energy decreasing in my atom simulation?

    F_i^j is the resultant force over the particle i in the j-chain. f_{LJ} is the corresponding magnitude.
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    Graduate Why is the energy decreasing in my atom simulation?

    Yeah I am tired changin the time step. And I'm not using a cutoff for the LJ potential.
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    Graduate Why is the energy decreasing in my atom simulation?

    Yes. I do not have an angular potential. And I calculate Lennard Jones potential over all particle pairs, except those that have an angle or a bond. In fact, in the most simple case, with M chains and 2 particles for every chain, I get the same thing. In fact, can we only discuss this...
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    Graduate Why is the energy decreasing in my atom simulation?

    By setting every positiion in terms of those coordinates I mentioned before? I don't understand the question.
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    Graduate Why is the energy decreasing in my atom simulation?

    Yeah, off corse. But what part ? There many lines of code.
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    Graduate Why is the energy decreasing in my atom simulation?

    No. It is not rotating.
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    Graduate Why is the energy decreasing in my atom simulation?

    Yeah, I compute all the velocities to one frame, my global frame.
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    Graduate Why is the energy decreasing in my atom simulation?

    No, I don't have velocity dependent forces, because my only forces are due to a Lennard-Jones Potential. I was a little confused. What I do really have is a rotating frame. Got it. I was not including the potential energy due to inertial centrifugal force. I was just including, kinetick energies...