在 pgfplot groupplot 中无法获得特定数据集的平滑图

Question

使用 groupplot 绘制两个具有公共 Y 轴的图时，除了一条曲线外，其余曲线都足够平滑。即使数据点增加，图中的步长保持不变。我试图将其平滑，但没有成功。在其他工具（例如 MS Excel）中绘制时，数据非常平滑。前言和代码部分如下。

\documentclass{standalone}
\usepackage{siunitx}
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{verbatim}
\usetikzlibrary{decorations}
\usetikzlibrary{decorations.markings}
\usetikzlibrary{plotmarks}
\usetikzlibrary{spy}
\usetikzlibrary{external}
\makeatletter
\tikzset{
    nomorepostactions/.code={\let\tikz@postactions=\pgfutil@empty},
    mymark/.style 2 args={decoration={markings,
            mark= between positions 0 and 1 step (1/20)*\pgfdecoratedpathlength with{%
                \tikzset{#2,every mark}\tikz@options
                \pgfuseplotmark{#1}%
            },  
        },
        postaction={decorate},
        /pgfplots/legend image post style={
            mark=#1,mark options={#2},every path/.append style={nomorepostactions}
        },
    },
}
\makeatother
\usepgfplotslibrary{colorbrewer}
\DeclareSIUnit\radpersec{\radian/\second}
    \usepgfplotslibrary{groupplots}
\begin{document}
    \begin{tikzpicture}
    \begin{groupplot}[
    group style={
        group size=2 by 1,
        y descriptions at=edge left,
        horizontal sep = 0pt,
    },

    ymode=log]
    \nextgroupplot[
    xmode=normal,
    width=8cm,
    height=10cm,
    xmin=-20,
    xmax=0,
    ymin=1,
    ymax=10000,
    xtick={-20, -10, 0},
    xticklabels={-20, -10, 0},
    ytick={1,2,3,4,5,6,7,8,9,1e1,2e1,3e1,4e1,5e1,6e1,7e1,8e1,9e1,1e2,2e2,3e2,4e2,5e2,6e2,7e2,8e2,9e2, 1e3,2e3,3e3,4e3,5e3,6e3,7e3,8e3,9e3, 1e4},
    yticklabels={$1$,,,,,,,,,$10$,,,,,,,,,$10^2$,,,,,,,,,$10^3$,,,,,,,,,$10^4$},
    xlabel={Imaginary part of wave vector $qL$},
    ylabel={frequency $\omega$ (\SI{}{\radian\per\second})},
    ]
    \addplot+ [color=red,thin, smooth, samples=10000] file{sem_complex_amm3.dat};
    \addplot+ [color=ForestGreen,thin] file{lmm_complex_amm2.dat};
    \nextgroupplot[
    xmode=normal,
width=8cm,
height=10cm,
legend style={draw=none, at={(0.8,0.3)}, legend cell align={left}, fill=none, anchor=north},
tick label style={font=\normalsize},
xmin=0,
xmax=3.1416,
xtick distance=1,
ytick distance=10^1,
ymin=1,
ymax=10000,
xtick={0,1.5708,3.14159},
xticklabels={0,$\frac{\pi}{2}$,$\pi$},
ytick={1,2,3,4,5,6,7,8,9,1e1,2e1,3e1,4e1,5e1,6e1,7e1,8e1,9e1,1e2,2e2,3e2,4e2,5e2,6e2,7e2,8e2,9e2, 1e3,2e3,3e3,4e3,5e3,6e3,7e3,8e3,9e3, 1e4},
%yticklabels={$1$,,,,,,,,,$10$,,,,,,,,,$10^2$,,,,,,,,,$10^3$,,,,,,,,,$10^4$,,},
xlabel={Real part of wave vector $qL$},
%ylabel={frequency $\omega$ (\SI{}{\radian\per\second})}, 
mark repeat={15},
]

    \addplot+ [color=red,very thin]    file{semamm_fifth_mode.dat};
\addplot+ [color=red,thin] file{AM_SEM.dat};
\legend{SEM};
\filldraw[draw=gray,fill=gray,opacity=0.2] (17,-50) rectangle (45,0);
\end{groupplot}
    \end{tikzpicture}
\end{document

此处 sem_complex_amm3.dat 是绘图不平滑的数据文件。如果有其他修复方法，请告诉我。