Sets the size of the figure by expanding the space of molecule.svg file. These dimension have been
        previously determined. Also makes the lines of the molecule thicker.

def add_bigger_box(self):
        """
        Sets the size of the figure by expanding the space of molecule.svg file. These dimension have been
        previously determined. Also makes the lines of the molecule thicker.
        """
        start1 = "width='"+str(int(self.molecule.molsize1))+"px' height='"+str(int(self.molecule.molsize2))+"px' >"
        start2 = "<rect style='opacity:1.0;fill:#FFFFFF;stroke:none' width='"+str(int(self.molecule.molsize1))+"' height='"+str(int(self.molecule.molsize2))+"' x='0' y='0'> </rect>"
        bigger_box ="width='100%' height='100%' viewbox='0 0 "+str(int(self.molecule.x_dim))+" "+str(int(self.molecule.y_dim))+"' > "
        big_box2= "<rect style='opacity:1.0;fill:white;stroke:none' width='"+str(int(self.molecule.x_dim))+"px' height='"+str(int(self.molecule.y_dim))+"px' x='0' y='0'> </rect> <g id='molecularDrawing' transform='translate("+str((self.molecule.x_dim-self.molecule.molsize1)/2)+","+str((self.molecule.y_dim-self.molecule.molsize2)/2)+")'>'<rect style='opacity:1.0;fill:#ffffff;stroke:none' width='"+str(self.molecule.molsize1)+"' height='"+str(self.molecule.molsize2)+"' x='0' y='0' /> "
        self.end_symbol = "</svg>"
        no_end_symbol = "</g>"
        #Make the lines in molecule drawing thicker to look better with the large plots
        linewidth1 = "stroke-width:2px"
        linewidth2 = "stroke-width:5px"
        self.change_lines_in_svg("molecule.svg", linewidth1,linewidth2)

        self.change_lines_in_svg("molecule.svg", start1, bigger_box)
        self.change_lines_in_svg("molecule.svg", start2, big_box2)
        self.change_lines_in_svg("molecule.svg", self.end_symbol, no_end_symbol)
        with open("molecule.svg","r") as f:
            lines = f.readlines()
            self.filestart = " ".join(map(str,lines[0:8]))
            self.draw_molecule ="".join(map(str,lines[8:]))
            f.close()