complex<double> V=0;
for (int nu=0; nu<4; nu++)
V += conf[ (*nb)[x*4+nu] ].phi;
conf[x].phi = sqrt(std::log( 1./(1-r) )) / sqrt(M)
complex<double> V=0;
for (int nu=0; nu<4; nu++)
V += conf[ (*nb)[x*4+nu] ].phi;
conf[x].phi = sqrt(std::log( 1./(1-r) )) / sqrt(M)