99 lines
2.8 KiB
Matlab
99 lines
2.8 KiB
Matlab
function [Params] = parameters()
|
|
%%--%% Parameters %%--%%
|
|
%========= Simulation =========%
|
|
pert=0; %0 = no perturbation during real-time, 1=perturbation
|
|
%method=1; %0 = normal dipolar potential, 1=spherical cut-off, 2=cylindrical cut-off
|
|
|
|
%Energy tolerance
|
|
Params.Etol=5e-10;
|
|
Params.rtol = 1e-5;
|
|
Params.theta=pi/2; %pi/2 dipoles along x, theta=0 dipoles along z
|
|
Params.cut_off=2e6; %sometimes the imaginary time gets a little stuck
|
|
%even though the solution is good, this just stops it going on forever
|
|
|
|
%========= Constants =========%
|
|
hbar = 1.0545718e-34; %Planck constant [J.s]
|
|
kbol = 1.38064852e-23; %Boltzmann Constant [J/K]
|
|
mu0 = 1.25663706212e-6; %Vacuum Permeability [N/A^2] --
|
|
muB = 9.274009994e-24; %Bohr Magneton [J/T]
|
|
a0 = 5.2917721067e-11; %Bohr radius [m]
|
|
m0 = 1.660539066e-27; %Atomic mass [kg]
|
|
w0 = 2*pi*100; %angular frequency unit [s^-1]
|
|
mu0factor = 0.3049584233607396;% =(m0/me)*pi*alpha^2 -- me=mass of electron, alpha=fine struct. const.
|
|
% mu0=mu0factor *hbar^2*a0/(m0*muB^2)
|
|
%=============================%
|
|
|
|
%Number of points in each direction
|
|
Params.Nx = 128;
|
|
Params.Ny = 128;
|
|
Params.Nz = 96;
|
|
|
|
%Dimensions (in units of l0)
|
|
Params.Lx = 40;
|
|
Params.Ly = 40;
|
|
Params.Lz = 20;
|
|
|
|
%Masses
|
|
Params.m = 162*m0;
|
|
l0 = sqrt(hbar/(Params.m*w0)); %Defining a harmonic oscillator length
|
|
|
|
%Atom numbers
|
|
% Params.ppum = 2500; %particles per micron
|
|
% Params.N = Params.Lz*Params.ppum*l0*1e6;
|
|
|
|
Params.N = 10^6;
|
|
|
|
%Dipole lengths (units of muB)
|
|
Params.mu = 9.93*muB;
|
|
|
|
%scattering lengths
|
|
Params.as = 86*a0;
|
|
|
|
%trapping frequencies
|
|
Params.wx = 2*pi*125;
|
|
Params.wy = 2*pi*125;
|
|
Params.wz = 2*pi*250;
|
|
|
|
%Time step
|
|
Params.dt = 0.0005;
|
|
Params.mindt = 1e-6; %Minimum size for a time step using adaptive dt
|
|
|
|
%Stochastic GPE
|
|
Params.gamma_S = 7.5*10^(-3); %gamma for the stochastic GPE
|
|
|
|
Params.muchem = 12.64*Params.wz/w0;
|
|
%================ Parameters defined by those above ================%
|
|
|
|
% == Calculating quantum fluctuations == %
|
|
eps_dd = Params.add/Params.as;
|
|
if eps_dd == 0
|
|
Q5 = 1;
|
|
elseif eps_dd == 1
|
|
Q5 = 3*sqrt(3)/2;
|
|
else
|
|
yeps = (1-eps_dd)/(3*eps_dd);
|
|
Q5 = (3*eps_dd)^(5/2)*( (8+26*yeps+33*yeps^2)*sqrt(1+yeps) + 15*yeps^3*log((1+sqrt(1+yeps))/sqrt(yeps)) )/48;
|
|
Q5 = real(Q5);
|
|
end
|
|
|
|
Params.gammaQF = 128/3*sqrt(pi*(Params.as/l0)^5)*Q5;
|
|
|
|
|
|
|
|
%Contact interaction strength (units of l0/m)
|
|
Params.gs = 4*pi*Params.as/l0;
|
|
|
|
%Dipole lengths
|
|
Params.add = mu0*Params.mu^2*Params.m/(12*pi*hbar^2);
|
|
|
|
%DDI strength
|
|
Params.gdd = 12*pi*Params.add/l0; %sometimes the 12 is a 4? --> depends on how Vdk (DDI) is defined
|
|
|
|
%Trap gamma
|
|
Params.gx=(Params.wx/w0)^2;
|
|
Params.gy=(Params.wy/w0)^2;
|
|
Params.gz=(Params.wz/w0)^2;
|
|
|
|
%Loading the rest into Params
|
|
Params.hbar = hbar; Params.kbol = kbol; Params.mu0 = mu0; Params.muB = muB; Params.a0 = a0;
|
|
Params.w0 = w0; Params.l0 = l0; |