标题：gulp
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GULP(General Utility Lattice Program )
GULP最初设计的目的是拟合立场，现在已经逐步发展成为模拟凝聚态物质的通用代码，可以模拟无机固体、团聚体、缺陷、表面、界面以及聚合物等。
GULP的功能如下：
模拟的类型-（各维的都能模拟）0-D (clusters and embedded defects) 
1-D (polymers) 
2-D (slabs and surfaces) 
3-D (bulk materials) 
能量最小化-（GULP里面比较出色的，方法也比较多）
constant pressure / constant volume / unit cell only / isotropic （恒压/恒容/单位晶胞/各向同性）
thermal/optical calculations （热/光学计算）
application of external pressure （应用外部压力）
user specification of degrees of freedom for relaxation （可以指定那些自由度要驰豫）r
elaxation of spherical region about a given ion or point （给定离子或质点的球形区域的驰豫）
symmetry constrained relaxation （对称性限制驰豫）
unconstrained relaxation （无限制驰豫）
constraints for fractional coordinates and cell strains （可对分数坐标和晶胞应力加限制）
Newton/Raphson, conjugate gradients or Rational Function optimisers （几种最小化算法）
BFGS or DFP updating of hessian （最小化算法，程序默认的）
limited memory variant of BFGS for large systems （对大体系的限制内存BFGS优化，L-BFGS）
search for minima by genetic algorithms with simulated annealing （遗传算法或模拟退火寻找最小）
free energy minimisation with analytic first derivatives （用解析一阶导数来最小化自由能）
choice of regular or domain decomposition algorithms for first derivative calculations （对于一阶导数采用规则或区域分解算法）
过渡态研究
location of -th order 
stationary points mode following 
晶体特性（这是GULP的一个重点）
elastic constants （弹性常数）
bulk modulus (Reuss/Voight/Hill conventions) 体积模量
shear modulus (Reuss/Voight/Hill conventions) 剪切模量
Youngs modulus 杨氏模量
Poisson ratios 泊松比
compressibility 压缩率
piezoelectric stress and strain constants 压电应力和应变常数
static dielectric constants 静止介电常数
high frequency dielectric constants 高频介电常数
frequency dependent dielectric constants 频率依赖介电常数
static refractive indices 静态折射系数
high frequency refractive indices 高频折射系数
phonon frequencies 声子频率
phonon densities of states (total and projected) 声子态密度
phonon dispersion curves 声子色散曲线
Born effective charges 波恩有效电荷
zero point vibrational energies 零点振动能
heat capacity (constant volume) 热容
entropy (constant volume) 熵
Helmholtz free energy 赫姆霍兹自由能 
缺陷计算（这也是GULP的一个特色）
vacancies, interstitials and impurities can be treated （空位、间隙和杂质）
explicit relaxation of region 1 （显式松弛）
implicit relaxation energy for region 2 （不明确驰豫能？）
energy minimisation and transition state calculations are possible （能量最小化和过渡态计算）
defect frequencies can be calculated (assuming no coupling with 2a)（缺陷频率）
表面计算
calculation of surface and attachment energies 表面能和吸附能
multiple regions allowed with control over rigid or unconstrained movement （刚体或无限制移动）
can be used to simulate grain boundaries 模拟晶界
calculation of phonons allowed for region 1 声子计算
力场拟合（GULP的老本行，也是很多人用它的最主要原因）
empirical fitting to structures, energies and most crystal properties （对结构、能量和大多数晶体特性的经验拟合）
fit to multiple structures simultaneously （同时拟合多个结构）
simultaneous relaxation of shell coordinates during fitting （拟合过程中同时驰豫shell坐标）
fit to structures by either minimising gradients or displacements （通过梯度最小化或位移最小化来拟合结构）
variation of potential parameters, charges and core/shell charge splits （势能参数变更，电荷和core/shell电荷分裂）
constraints available for fitted parameters （可以对拟合参数施加限制）
generate initial parameter sets by the genetic algorithm for subsequent refinement （通过遗传算法生成用于随后精修的初始参数）
fit to quantum mechanically derived energy hypersurfaces （对量子力学导出的能量超曲面拟合）
结构分析
calculate bond lengths/distances （键长和距离）
calculate bond angles 键角
calculate torsion angles 扭转角
calculate out of plane distances  （out of plane 距离） 
calculation of the density and cell volume （晶胞密度和体积）
electrostatic site potentials （静电位置势能）
electric field gradients 电场梯度
结构操作
convert centred cell to primitive form （转换为素晶胞）
creation of supercells 创建超晶胞
电负性平衡　　
use EEM to calculate charges for systems containing H, C, N, O, F, Al, Si, P 
use QEq to calculate charges for any element 
new modified scheme for hydrogen within QEq that has correct forces 
可以输出的格式
GDIS (.gin/.res) 
THBREL/THBPHON/CASCADE (.thb) 
MARVIN (.mvn) 
Insight (.xtl file) I
nsight (.arc/.car files) 
G-Vis (.xr) 
Cerius2 (.arc/.xtl/.cssr) 
Materials Studio 
SIESTA (.fdf) 
Molden (.xyz) 
QMPOT (.frc) 
General (.cif/.xml) 
DLV (.str) 
分子动力学模拟（GULP的这一块是比较弱的，只是最基本的动力学代码，可以说算法不是很强壮，容易出错）
Shell model (dipolar and breathing) molecular dynamics （shell模型的分子动力学模拟）
Finite mass or adiabatic algorithms 有限的质量和绝热算法
Forward extrapolation of shells added for adiabatic algorithms 增加到绝热算法的shell的前推
NVE or NVT (Nose-Hoover) or NPT (Variable cell shape) 
蒙特卡罗模拟
Rigid molecules allowed for  允许刚性分子
Displacement or rotation of species 物种的旋转或位移
NVT or Grand Canonical ensembles allowed NVT或巨正则系宗[1]