dispersion.pl6 added

scripts/dispersion.pl6

+#!/usr/bin/perl6
+
+use v6;
+
+sub MAIN(Int $L, $t, $r, Str $bc = "open")
+{
+	my $tpr = $t + $r;
+	my $tmr = $t - $r;
+	my @disp;
+	for 0..^$L -> Int $mm {
+		my $m = ($bc eq "periodic") ?? $mm !! $mm + 1;
+		my $sk = -2.0*cos(findKdependence($m, $L, $bc));
+		my $e = $tpr*$sk;
+		push @disp, $e;
+		$e = $tmr*$sk;
+		push @disp, $e;
+	}
+
+	my @disp2 = @disp.sort;
+	say "Eigenvalues: ";
+	say @disp2.join(' ');
+	say "Full Energies: ";
+	say sumEnergies(@disp2).join("\n");
+}
+
+sub sumEnergies(@disp)
+{
+	my @a;
+	my $sum = 0;
+	my $n = @disp.elems;
+	for 0..^$n -> Int $ind {
+		$sum += @disp[$ind];
+		my Int $jnd = $ind + 1;
+		push @a, "$jnd\t$sum";
+	}
+
+	return @a;
+}
+
+sub findKdependence($m, $L, $bc)
+{
+	return ($bc eq "periodic") ?? kperiodic($m, $L) !! kopen($m, $L);
+}
+
+sub kperiodic($m, $L)
+{
+	2.0*$m*pi/$L;
+}
+
+sub kopen($m, $L)
+{
+	$m*pi/($L + 1);
+}
+
+