How to make halo around node with shading?

Question

I am trying to do this (do not pay attention to red line above blue node and line in the node):

By so far i have this:

With this code:

\documentclass[tikz,12pt]{standalone}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[english,french,russian]{babel}
\usepackage{chemfig}
\usepackage{mathptmx}
\usepackage{esvect}
\usepackage{tikz}
\usetikzlibrary{arrows,decorations.pathmorphing,decorations.pathreplacing,shadows,calc,decorations.markings} 
\usetikzlibrary{shapes,shadows}
\usetikzlibrary{intersections}
\usetikzlibrary{positioning}
\definecolor{Green}{RGB}{0,220,70}
\tikzstyle{vecArrow} = [thick, decoration={markings,mark=at position
1 with {\arrow[semithick,fill=blue]{triangle 60}}}, double distance=1.8pt, shorten >= 5.5pt,
preaction = {decorate},
postaction = {draw,line width=1.4pt, white,shorten >= 4.5pt}]

\tikzstyle{vecArrowBlue} = [thick, decoration={markings, mark=at position
   1 with {\arrow[semithick, fill=blue]{triangle 60}}},
   double distance=1.4pt, shorten >= 5.5pt,
   preaction = {decorate},
   postaction = {draw, line width=1.4pt, blue, shorten >= 4.5pt}]

\begin{document}
\begin{tikzpicture}[font=\small,line width=1pt,node distance=0]
\tikzset{line width=2pt}

\node[draw,line width=2pt,rounded corners=4pt,minimum width=0.5cm, minimum height=.8cm,shade, shading=axis, top color=Green, bottom color=blue!80,shading angle=0,circular drop shadow={color=red!60!black}] (box) at (0,0) {};

\draw[vecArrowBlue] ($(box.south)+(0,3pt)$) to ($(box.north)-(0,3pt)$);
\end{tikzpicture}
\end{document}

Is there a way to make halo around node? I've tried shadow without any success.

Thank you in advance.

Answer 1

I've searched a lot and combined my code with code of examples. Finally I've got this:

\documentclass[tikz,12pt]{standalone}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[english,french,russian]{babel}
\usepackage{chemfig}
\usepackage{mathptmx}
\usepackage{esvect}
\usepackage{tikz}
\usetikzlibrary{arrows,decorations.pathmorphing,decorations.pathreplacing,shadows,calc,decorations.markings} 
\usetikzlibrary{shapes,shadows}
\usetikzlibrary{intersections}
\usetikzlibrary{positioning}
\definecolor{Green}{RGB}{0,220,70}
\tikzstyle{vecArrow} = [thick, decoration={markings,mark=at position
1 with {\arrow[semithick,fill=blue]{triangle 60}}}, double distance=1.8pt, shorten >= 5.5pt,
preaction = {decorate},
postaction = {draw,line width=1.4pt, white,shorten >= 4.5pt}]

\tikzstyle{vecArrowBlue} = [thick, decoration={markings, mark=at position
   1 with {\arrow[semithick, fill=blue]{triangle 60}}},
   double distance=1.4pt, shorten >= 5.5pt,
   preaction = {decorate},
   postaction = {draw, line width=1.4pt, blue, shorten >= 4.5pt}]

\begin{document}
\def\shadowshift{0pt,0pt}
\def\shadowradius{35pt}

% this draws a shadow under a rectangle node
\newcommand\drawshadow[1]{
    \begin{pgfonlayer}{shadow}
        \shade[red,inner color=red,outer color=white] ($(#1.center)$)        circle (\shadowradius);

    \end{pgfonlayer}
}

% create a shadow layer, so that we don't need to worry about overdrawing other things
\pgfdeclarelayer{shadow} 
\pgfsetlayers{shadow,main}   
\begin{tikzpicture}[font=\small,line width=1pt,node distance=0]
\tikzset{line width=2pt}  
\tikzset{
 shrink inner sep/.code={
   \pgfkeysgetvalue{/pgf/inner xsep}{\currentinnerxsep}
   \pgfkeysgetvalue{/pgf/inner ysep}{\currentinnerysep}
   \pgfkeyssetvalue{/pgf/inner xsep}{\currentinnerxsep - 0.5\pgflinewidth}
   \pgfkeyssetvalue{/pgf/inner ysep}{\currentinnerysep - 0.5\pgflinewidth}
   }
}
\tikzset{horizontal shaded border/.style args={#1 and #2}{
    append after command={
       \pgfextra{%                 
          \begin{pgfinterruptpath}
                \path[rounded corners,left color=#1,right color=#2]
                ($(\tikzlastnode.south west)+(-\pgflinewidth,-\pgflinewidth)$) 
                rectangle
                ($(\tikzlastnode.north east)+(\pgflinewidth,\pgflinewidth)$);        
           \end{pgfinterruptpath}
        } 
    }
  },
  vertical shaded border/.style args={#1 and #2}{
    append after command={
       \pgfextra{%                 
          \begin{pgfinterruptpath}
                \path[rounded corners,top color=#1,bottom color=#2]
                ($(\tikzlastnode.south west)+(-\pgflinewidth,-\pgflinewidth)$) 
                rectangle
                ($(\tikzlastnode.north east)+(\pgflinewidth,\pgflinewidth)$);        
           \end{pgfinterruptpath}
        } 
    }
  }
}

\node[rectangle,
      rounded corners,thick,shrink inner sep,minimum width=0.5cm, minimum height=.8cm,shade, shading=axis, top color=Green, bottom color=blue!80!red!50,shading angle=0,vertical shaded border=Green and blue!80!red!50] (box) at (0,0) {};
\drawshadow{box}   
\draw[vecArrowBlue] ($(box.south)+(0,3pt)$) to ($(box.north)-(0,3pt)$);
\end{tikzpicture}
\end{document}