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GULP(General Utility Lattice Program )

GULP最初設計的目的是擬合立場，現在已經逐步發展成為模擬凝聚態物質的通用代碼，可以模擬無機固體、團聚體、缺陷、表面、界面以及聚合物等。
GULP的功能如下：
模擬的類型-（各維的都能模擬）0-D (clusters and embedded defects)
1-D (polymers)
2-D (slabs and surfaces)
3-D (bulk materials)
能量最小化-（GULP裡面比較出色的，方法也比較多）
constant pressure / constant volume / unit cell only / isotropic （恆壓/恆容/單位晶胞/各向同性）
thermal/optical calculations （熱/光學計算）
application of external pressure （套用外部壓力）
user specification of degrees of freedom for relaxation （可以指定那些自由度要馳豫）r
elaxation of spherical region about a given ion or point （給定離子或質點的球形區域的馳豫）
symmetry constrained relaxation （對稱性限制馳豫）
unconstrained relaxation （無限制馳豫）
constraints for fractional coordinates and cell strains （可對分數坐標和晶胞應力加限制）
Newton/Raphson, conjugate gradients or Rational Function optimisers （幾種最小化算法）
BFGS or DFP updating of hessian （最小化算法，程式默認的）
limited memory variant of BFGS for large systems （對大體系的限制記憶體BFGS最佳化，L-BFGS）
search for minima by genetic algorithms with simulated annealing （遺傳算法或模擬退火尋找最小）
free energy minimisation with analytic first derivatives （用解析一階導數來最小化自由能）
choice of regular or domain decomposition algorithms for first derivative calculations （對於一階導數採用規則或區域分解算法）
過渡態研究
location of -th order
stationary points mode following
晶體特性（這是GULP的一個重點）
elastic constants （彈性常數）
bulk modulus (Reuss/Voight/Hill conventions) 體積模量
shear modulus (Reuss/Voight/Hill conventions) 剪下模量
Youngs modulus 楊氏模量
Poisson ratios 泊松比
compressibility 壓縮率
piezoelectric stress and strain constants 壓電應力和應變常數
static dielectric constants 靜止介電常數
high frequency dielectric constants 高頻介電常數
frequency dependent dielectric constants 頻率依賴介電常數
static refractive indices 靜態折射係數
high frequency refractive indices 高頻折射係數
phonon frequencies 聲子頻率
phonon densities of states (total and projected) 聲子態密度
phonon dispersion curves 聲子色散曲線
Born effective charges 波恩有效電荷
zero point vibrational energies 零點振動能
heat capacity (constant volume) 熱容
entropy (constant volume) 熵
Helmholtz free energy 赫姆霍茲自由能
缺陷計算（這也是GULP的一個特色）
vacancies, interstitials and impurities can be treated （空位、間隙和雜質）
explicit relaxation of region 1 （顯式鬆弛）
implicit relaxation energy for region 2 （不明確馳豫能？）
energy minimisation and transition state calculations are possible （能量最小化和過渡態計算）
defect frequencies can be calculated (assuming no coupling with 2a)（缺陷頻率）
表面計算
calculation of surface and attachment energies 表面能和吸附能
multiple regions allowed with control over rigid or unconstrained movement （剛體或無限制移動）
can be used to simulate grain boundaries 模擬晶界
calculation of phonons allowed for region 1 聲子計算
力場擬合（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 （對結構、能量和大多數晶體特性的經驗擬合）
fit to multiple structures simultaneously （同時擬合多個結構）
simultaneous relaxation of shell coordinates during fitting （擬合過程中同時馳豫shell坐標）
fit to structures by either minimising gradients or displacements （通過梯度最小化或位移最小化來擬合結構）
variation of potential parameters, charges and core/shell charge splits （勢能參數變更，電荷和core/shell電荷分裂）
constraints available for fitted parameters （可以對擬合參數施加限制）
generate initial parameter sets by the genetic algorithm for subsequent refinement （通過遺傳算法生成用於隨後精修的初始參數）
fit to quantum mechanically derived energy hypersurfaces （對量子力學導出的能量超曲面擬合）
結構分析
calculate bond lengths/distances （鍵長和距離）
calculate bond angles 鍵角
calculate torsion angles 扭轉角
calculate out of plane distances （out of plane 距離）
calculation of the density and cell volume （晶胞密度和體積）
electrostatic site potentials （靜電位置勢能）
electric field gradients 電場梯度
結構操作
convert centred cell to primitive form （轉換為素晶胞）
creation of supercells 創建超晶胞
電負性平衡　
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
可以輸出的格式
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)
分子動力學模擬（GULP的這一塊是比較弱的，只是最基本的動力學代碼，可以說算法不是很強壯，容易出錯）
Shell model (dipolar and breathing) molecular dynamics （shell模型的分子動力學模擬）
Finite mass or adiabatic algorithms 有限的質量和絕熱算法
Forward extrapolation of shells added for adiabatic algorithms 增加到絕熱算法的shell的前推
NVE or NVT (Nose-Hoover) or NPT (Variable cell shape)
蒙特卡羅模擬
Rigid molecules allowed for 允許剛性分子
Displacement or rotation of species 物種的旋轉或位移
NVT or Grand Canonical ensembles allowed NVT或巨正則系宗