Back (Current repo: kronig-penney)

commit b8ac6945b21f9de3576b3f40873c0d4df04e2dbd
Author: root <root>
Date:   Tue, 12 Aug 2025 01:56:22 +0200

create files

Diffstat:
A
kp.c
 | 
69
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
kp.h
 | 
3
+++
A
kp_py.c
 | 
38
++++++++++++++++++++++++++++++++++++++

3 files changed, 110 insertions(+), 0 deletions(-)
diff --git a/kp.c b/kp.c
@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include <math.h>
+#include <complex.h>
+#include "kp.h"
+
+void solve(const double E, double complex k[2], double b, double V_0, double Delta) {
+    double complex q = csqrt(2.0 * E);
+    double complex kappa = csqrt(2.0 * (E - V_0));
+
+    double complex psi_11, psi_12, psi_21, psi_22;
+
+    psi_11 = cexp(I * q * (b - Delta)) / (4.0 * q * kappa)
+        * ( cexp(I * kappa * Delta)   * (q + kappa) * (q + kappa)
+          - cexp(-I * kappa * Delta)  * (q - kappa) * (q - kappa) );
+
+    psi_22 = conj(psi_11);
+
+    psi_12 = -I * cexp(I * q * (b - Delta)) / (2.0 * q * kappa)
+        * (q * q - kappa * kappa) * csin(kappa * Delta);
+
+    psi_21 = conj(psi_12);
+
+    // quadratic determinantal eqn
+    double complex u = -(psi_11 + psi_22);
+    double complex v = (psi_11 * psi_22 - psi_12 * psi_21);
+    double complex lam[2];
+
+    lam[0] = (-u + csqrt(u * u - 4.0 * v)) / 2.0;
+    lam[1] = (-u - csqrt(u * u - 4.0 * v)) / 2.0;
+
+    for (int x = 0; x < 2; x++) {
+        k[x] = clog(lam[x]) / (I * b);
+    }
+}
+
+void gen_data(double b, double V_0, double Delta) {
+    const double pi = 4.0 * atan(1.0);
+    const double dE = 0.01;
+    double E = dE;
+    const int N = 3000;
+
+    FILE *fp = fopen("data.csv", "w");
+    if (!fp) {
+        fp = fopen("/dev/null", "w");
+    } 
+
+    for (int y = 0; y < N; y++) {
+        double complex q[2];
+        solve(E, q, b, V_0, Delta);
+
+        double rq = creal(q[0]);
+
+        if (rq > 0 && rq < pi / b) {
+            fprintf(fp, "%.15g,%.15g\n", rq, E);
+            fprintf(fp, "%.15g,%.15g\n", -rq, E);
+        }
+
+        rq = creal(q[1]);
+
+        if (rq > 0 && rq < pi / b) {
+            fprintf(fp, "%.15g,%.15g\n", rq, E);
+            fprintf(fp, "%.15g,%.15g\n", -rq, E);
+        }
+
+        E += dE;
+    }
+
+    fclose(fp);
+}
diff --git a/kp.h b/kp.h
@@ -0,0 +1,3 @@
+#include <complex.h>
+
+void gen_data(double b, double V_0, double Delta);
diff --git a/kp_py.c b/kp_py.c
@@ -0,0 +1,38 @@
+#define PY_SSIZE_T_CLEAN
+#include <Python.h>
+#include <complex.h>
+#include "kp.h"
+
+static PyObject* py_gen_data(PyObject* self, PyObject* args, PyObject* kwargs) {
+    static char* kwlist[] = {"b", "V_0", "Delta", NULL};
+    double b = 1.0, V_0 = -5.0, Delta = 0.2;
+
+    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "|ddd", kwlist, &b, &V_0, &Delta)) {
+        return NULL;
+    }
+
+    gen_data(b, V_0, Delta);
+
+    Py_RETURN_NONE;
+}
+
+static PyMethodDef KPMethods[] = {
+    {"gen_data", (PyCFunction)py_gen_data, METH_VARARGS | METH_KEYWORDS,
+     "gen_data(b=1.0, V_0=-5.0, Delta=0.2) -> None\n"
+     "Generates ./data.csv using hardcoded path; silent on I/O failure."},
+    {NULL, NULL, 0, NULL}
+};
+
+static struct PyModuleDef kp_module = {
+    PyModuleDef_HEAD_INIT,
+    "kp",
+    "Kronig–Penney data generator",
+    -1,
+    KPMethods
+};
+
+PyMODINIT_FUNC PyInit_kp(void) {
+    return PyModule_Create(&kp_module);
+}
+
+