In fact, I want to write a manual nomenclature inside a chapter that I named list of abbreviations, when I write that nomenclatures they are not aligned and there is a space in the beginning of the first nomenclature. Here is the code:
\documentclass[12pt]{report}
\usepackage{lipsum}
\usepackage[intoc]{nomencl}
\makenomenclature
\usepackage[french]{babel}
\usepackage{unnumberedtotoc}
\usepackage[automark,
plainheadsepline,
headsepline,
plainfootsepline,
footsepline,
markcase=ignoreupper]{scrlayer-scrpage}
\clearpairofpagestyles
\ihead*{\leftmark}
\cfoot*{\pagemark}
\setkomafont{pageheadfoot}{\scshape}
\usepackage{titlesec}
\usepackage[a4paper,right=20mm,left=25mm,top=30mm, bottom=40mm,%
head=14.5pt,%<- new
]{geometry}
\titleformat{\chapter}[display]
{\normalfont\huge\bfseries}{\chaptertitlename\ \thechapter}{20pt}{\Huge}
\titlespacing*{\chapter}{0pt}{0pt}{20pt}
\titleformat{\paragraph}
{\normalfont\normalsize\bfseries}{\theparagraph}{1em}{}
\titlespacing*{\paragraph}
{0pt}{3.25ex plus 1ex minus .2ex}{1.5ex plus .2ex}
\begin{document}
\tableofcontents
\addchap{Publications}
\addchap{Acknowledgement}
\printnomenclature
\nomenclature{FCB}{FC Barcelona}
\nomenclature{ASR}{AS Roma}
\nomenclature{FCS}{FC Sévilla}
\nomenclature{FCB}{FC Bayern}
\nomenclature{JFC}{Juventus FC}
\nomenclature{LFC}{Liverpool FC}
\nomenclature{MC}{Manchester City}
\chapter{Introduction}
\lipsum
\lipsum
\chapter{state of art}
\lipsum
\chapter{theory}
\lipsum
\end{document}


nomenclorglossaries)? If you insist on a manual nomenclature, I would suggest using atabularor evenlongtableenvironment to ensure a correct alignment of the abbreviations and their descriptions. Please also make your example a minimal working example (MWE). There are a lot of packages that are not needed to reproduce the issue you describe. – leandriis Mar 18 '18 at 20:04\begin{array}is essentially a\begin{tabular}for the usage inside of a math-environment. You should usetabularorlongtableif your nomenclature is longer than a single page. Alternatively you might be able to setup a nice looking nomenclature usingdescription(maybe with theenumitempackage to change the formatting a bit). – Skillmon Mar 18 '18 at 20:36