simple_hopping.cpp

#include "hila.h"
 
static_assert(NDIM == 3, "NDIM must be 3 here");
 
using MyType = Complex<double>;
 
int main(int argc, char *argv[]) {
 
    // initialize system
    hila::initialize(argc, argv);
 
    // set up the lattice
    lattice.setup({128, 128, 128});
 
    // Random numbers are used here - use time to seed
    hila::seed_random(0);
 
    // lattice field
    Field<MyType> f;
    // make f Gaussian random distributed
    onsites(ALL) f[X].gaussian_random();
 
    // Measure hopping term and f^2
    MyType hopping = 0;
    double fsqr = 0;
    
    onsites(ALL) {
        foralldir(d) {
            hopping += f[X] * f[X + d].dagger();
        }
        fsqr += f[X].squarenorm();
    }
    hila::out0 << "Average f^2 : " << fsqr / lattice.volume() << '\n';
    hila::out0 << "Average hopping term " << hopping / (NDIM*lattice.volume()) << '\n';
 
    hila::finishrun();
    return 0;
}