ButterAddict

ButterAddict
黄油上瘾

科学而不失偏见的大杂烩

Hi guys, this is Minghao Zhang, aka Tiger / 2LalA. I am an graduate scientist at Cambridge.
ButterAddict is not only the title of my leisure blogging site, but also a life philosophy.

Electrons and Solids
Cambridge IB Chemistry course with some IB Physics blended in. Ionic ModelIn the lattice, ions experience the force from neighbours, next-neighbours, next-next-neighbours, …, forming a conditionally convergent series. The sum is (or rather from experimental data is deduced to be) Madelung const...
Fourier Transform
This is a only a summary of knowledge. Fourier transformThere are many conventions as in where to put the normalisation 2\pi factor. Forward Fourier transform (Fourier analysis) \tilde{f}(k)=\int_{-\infty}^\infty f(x)e^{-ikx}\,dx Inverse Fourier transform (Fourier synthesis) f(x)=\frac{1}...
Functionals
FunctionalsJust like functions take variables as arguments, functionals take functions as arguments. In the following sections, the functional of the form G[y]=\int_\alpha^\beta f(y,y' ; x) \, dxis considered. Functional derivativesDefinition: \begin{align} \delta G &= G[y+\delta y]-G[y]\\ &=\...
Differential Equations
Key concepts Linear operator Homogeneous: equation: no forcing, or, a multiple of a solution y, \alpha y is also a solution. problem: in addition, \alpha y also satisfies B.C. Boundary conditions Dirichlet: the function value on the boundary is defined Neumann: the normal derivative value on t...
Matrix & Tensor
MatricesVector spaceDefinition A set of elements on which vector addition and scalar multiplication are defined Closed under these operations Includes identity \mathbf{0}​ for vector addition Note: 2D spaces \mathbb{R}^2 \neq \mathbb{C}, since \mathbb{C} has a single point of \infty. SpanThe s...
Contour Integration
Contour IntegrationIdea: A powerful method of doing integrals by using the properties of complex functions. Analytic functions To be differentiable at a point, a function must satisfy Cauchy-Riemann. \frac{\partial u}{\partial x} = \frac{\partial v}{\partial y}, \,\frac{\partial v}{\partial x} ...
IB Spectroscopy Techniques
Overall pictureScale Type Energy scale / \pu{cm-1} EM wave Electronic 10000 UV/VIS, X-ray Vibration 1000 IR Rotation 1 Microwave Requirements Rotation (Microwave) Spectra Need permanent dipole x, y or z transforms as totally symmetric representation Infrared Need change in di...
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Steve: 'Stay hungry, stay foolish.' Me: 'Eat well, don't be stupid.'
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