physics.sty

% preamble
\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{physics}[2012/06/17 Definitions for physics]
% packages
\RequirePackage{basic}

% definition equal sign
\let\eqdef\equiv
% complex operators
\let\Re\relax
\let\Im\relax
\DeclareMathOperator\Re{Re}
\DeclareMathOperator\Im{Im}

% differential with a bar
\newcommand*\dbar{\mathrlap{\m@th\mkern3mu\mathchar"0016}d}
% order of expansion
\newcommand*\ord[1]{^{(#1)}}

% d'Alembert operator
\DeclareMathOperator\dalm\square
% common physical constants
\newcommand*\kB{k_\su B}
\newcommand*\sigmaSB{\sigma_\su{SB}}
\newcommand*\sigmaT{\sigma_\su T}
\newcommand*\kappaT{\kappa_\su T}
\newcommand*\prmt{\epsilon_0}
\newcommand*\prmb{\mu_0}
\newcommand*\econst{\frac1{4\pi|\prmt}}
\newcommand*\mconst{\frac\prmb{4\pi}}
\newcommand*\muB{\mu_\su B}

% bra--ket notation
\newcommand*\bra[1]{\langle#1\futurelet\@tempa\phy@checkket}
\newcommand*\phy@checkket{\ifx\@tempa\ket\else\rvert\fi}
\newcommand*\ket[1]{\lvert#1\rangle}
% operator
\let\op\hat
% Hermitian adjoint
\newcommand*\adj{^\dag}
% commutator and anti-commutator
\DeclarePairedDelimiterX\comm[2][]{#1,#2}
\DeclarePairedDelimiterX\acmm[2]\{\}{#1,#2}
% spin-up and spin-down
\mathchardef\up"0222
\mathchardef\down"0223

% field-theory definitions
\newcommand*\fvec[1]{\boldsymbol{\mathsf{#1}}}
\newcommand*\ufvec[1]{\hat{\fvec{#1}}}
\@ifpackageloaded{simplewick}{
  \def\phy@split#1#2#3#4\@nil{\def#1{#3}\def#2{#4}}
  \newcommand*\wick[2]{\begingroup
    \phy@split\@tempc\@tempb#2\@nil
    \phy@split\@tempa\@tempb#1\@nil
    \contraction{\hskip-0.025em}{\@tempa\vphantom{\@tempc}}\@tempb\@tempc#1|#2%
  \endgroup}
}{}
\@ifpackageloaded{tensor}{
  \DeclareSimpleTensor\gmat\gamma1
  \DeclareSimpleTensor\smat\sigma1
  \DeclareSimpleTensor\sbmat{\bar\sigma}1
}{}

% elements and particles
\let\element\textup
\let\particle\textup