How to use tab split and tab merge

I wanna tab split and merge by shortcut, so I insert this sentence in .vimrc

" Ctrl + w + T : tab split

""""""""" tab merge """"""""""

nmap <C-W><S-M> :let this_tab = bufname(%) | exe 'normal! gt' | exe 'vsplit ' . this_tab | exe "normal! gT" | q | unlet this_tab<cr><cr>