diff --git a/dpgen/data/model1.cif b/dpgen/data/P3ma/model1.cif
similarity index 100%
rename from dpgen/data/model1.cif
rename to dpgen/data/P3ma/model1.cif
diff --git a/dpgen/data/model2.cif b/dpgen/data/P3ma/model2.cif
similarity index 100%
rename from dpgen/data/model2.cif
rename to dpgen/data/P3ma/model2.cif
diff --git a/dpgen/data/model3.cif b/dpgen/data/P3ma/model3.cif
similarity index 100%
rename from dpgen/data/model3.cif
rename to dpgen/data/P3ma/model3.cif
diff --git a/dpgen/data/model4.cif b/dpgen/data/P3ma/model4.cif
similarity index 100%
rename from dpgen/data/model4.cif
rename to dpgen/data/P3ma/model4.cif
diff --git a/dpgen/data/origin.cif b/dpgen/data/P3ma/origin.cif
similarity index 100%
rename from dpgen/data/origin.cif
rename to dpgen/data/P3ma/origin.cif
diff --git a/dpgen/transport.py b/dpgen/transport.py
new file mode 100644
index 0000000..12f1c47
--- /dev/null
+++ b/dpgen/transport.py
@@ -0,0 +1,76 @@
+from typing import List, Dict, Tuple
+
+def add_li_y_antisite_average(
+    x: float,
+    # Y 位点：[(label, wyckoff, (fx,fy,fz), occ, multiplicity)]
+    y_sites: List[Tuple[str, str, Tuple[float, float, float], float, int]] = None,
+    # Li 位点：[(label, wyckoff, (fx,fy,fz), occ, multiplicity)]
+    li_sites: List[Tuple[str, str, Tuple[float, float, float], float, int]] = None,
+    # 可选：各位点的 B 因子（字典），不需要可留空
+    b_iso: Dict[str, float] = None,
+    # 保留小数位
+    ndigits: int = 4
+) -> str:
+    """
+    把结构改写成含 x (相对于 Y 总数) 的 Li/Y 反位缺陷的“平均占据”CIF 块。
+    返回字符串，可直接粘贴到 CIF 的 atom_site loop 中。
+    """
+    # 默认使用表 S9（P-3̅m1）的坐标与占据；multiplicity 依据该空间群
+    if y_sites is None:
+        y_sites = [
+            ("Y1", "1a", (0.0000, 0.0000, 0.0000), 1.0000, 1),
+            ("Y2", "2d", (0.3333, 0.6666, 0.4880), 0.8269, 2),
+            ("Y3", "2d", (0.3333, 0.6666,-0.0650), 0.1730, 2),
+        ]
+    if li_sites is None:
+        li_sites = [
+            ("Li1", "6g", (0.3397, 0.3397, 0.0000), 1.0000, 6),
+            ("Li2", "6h", (0.3397, 0.3397, 0.5000), 0.5000, 6),
+        ]
+    if b_iso is None:
+        # 可按需要改
+        b_iso = {"Y": 1.10, "Li": 5.00, "Cl": 1.99}
+
+    # 1) 总 Y 与总 Li（每原胞的“原子数贡献”）：
+    y_total = sum(m * occ for _,_,_,occ,m in y_sites)   # 期望为 3
+    li_total = sum(m * occ for _,_,_,occ,m in li_sites) # 期望为 9
+
+    # 2) 需要交换的“Y 数量”（相对于每原胞）
+    y_exchanged = x * y_total   # 例如 x=0.0556 → ~0.1668 个 Y/原胞
+
+    # 3) 折算到 Li 子格的分配比例（保证电中性和计量）
+    li_fraction = y_exchanged / li_total  # 每个 Li 位点应引入的 Y 的比例
+
+    # 4) 生成 CIF loop 文本（同一坐标写两行，分别为主元素与反位元素）
+    lines = []
+    header = [
+        "loop_",
+        " _atom_site_label",
+        " _atom_site_type_symbol",
+        " _atom_site_fract_x",
+        " _atom_site_fract_y",
+        " _atom_site_fract_z",
+        " _atom_site_occupancy",
+        " _atom_site_B_iso_or_equiv",
+    ]
+    lines.extend(header)
+
+    # 4a) 处理 Y 位点：Y → (1-x)*occ；Li_on_Y → x*occ
+    for label, wyck, (fx,fy,fz), occ, mult in y_sites:
+        y_main_occ = round(occ * (1.0 - x), ndigits)
+        li_on_y_occ = round(occ * x, ndigits)
+        lines.append(f" {label}_main   Y    {fx:.4f}    {fy:.4f}    {fz:.4f}    {y_main_occ:.{ndigits}f}    {b_iso.get('Y',1.0)}")
+        lines.append(f" Li_on_{label}  Li   {fx:.4f}    {fy:.4f}    {fz:.4f}    {li_on_y_occ:.{ndigits}f}    {b_iso.get('Li',5.0)}")
+
+    # 4b) 处理 Li 位点：Li → (1-li_fraction)*occ；Y_on_Li → li_fraction*occ
+    for label, wyck, (fx,fy,fz), occ, mult in li_sites:
+        li_main_occ = round(occ * (1.0 - li_fraction), ndigits)
+        y_on_li_occ = round(occ * li_fraction, ndigits)
+        lines.append(f" {label}_main   Li   {fx:.4f}    {fy:.4f}    {fz:.4f}    {li_main_occ:.{ndigits}f}    {b_iso.get('Li',5.0)}")
+        lines.append(f" Y_on_{label}   Y    {fx:.4f}    {fy:.4f}    {fz:.4f}    {y_on_li_occ:.{ndigits}f}    {b_iso.get('Y',1.0)}")
+
+    return "\n".join(lines)
+
+# === 示例 ===
+# x=0.0556（与论文使用的 5.56% 一致，定义为相对于 Y 总数的比例）：
+print(add_li_y_antisite_average(0.0556))
\ No newline at end of file