function psi = Gaussian(location)
% 1D Gaussian initial condition.
global Rf Wf Lf
x = location.x;
y = location.y;

% Set parameters. 'sig' is \bar{\sigma} from the paper and is in \ell. k0 is k_0, and is in 1/\ell.
sig = 5;
k0 = 1;
psi = exp(-k0*1i*x).*exp(-(x+Rf/2).^2/4/sig^2); % Note that x is shifted by +Rf/2. This centers the wavepacket in the middle of R_1. Can change initial position if you like...
