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MOLCAS

張貼者:2010年9月18日 下午10:10未知的使用者   [ eddie liu 已於 2011年5月10日 下午8:27 更新 ]
量子化學程序MOLCAS可以用各種量子化學模型研究分子體系,從SCF/DFT到耦合簇,從RASSCF到包含動態電子相關處理的MR-CI或MS-CASPT2,而且包含動態相關處理的多組態密度泛函理論(CAS-DFT)。 MOLCAS的重點在於多組態的量子化學計算,用於研究單組態不能給出電子結構合理描述的體系,例如激發態,化學反應的過渡態,重元素體系(過渡金屬,鑭系,錒系)等。 MOLCAS的另一特點是多組態級別的相對論處理(標量相對論和自旋-軌道耦合),並提供專門為相對論計算設計的基組。





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開發商:MOLCAS
原廠網址:http://www.teokem.lu.se/molcas/features.html
更新日期:2011/05/11
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Molcas功能

波函數,能量,性質
MOLCAS使用下面的波函數在計算模型的總能量,電子結構和分子特性:
  • 的Hartree - Fock相結合的DFT。 直接或半直接計劃使用,這使得有可能在這個水平計算,超過1萬的基礎功能。
  • 多體微擾理論二階(關閉或限制開殼層)可用於廉價的估計動態電子相關效應。
  • Multiconfigurational超臨界流體(中國科學院或RAS)是用於治療系統的電子結構的地方沒有很好地描述了一個決定因素。 允許國家平均為治療許多電子態。波函數高達約1億美元的電子配置可以進行研究。
  • Multiconfigurational二階微擾理論(CASPT2)可以用來估計動態電子相關的電子態與CASSCF方法獲得。 阿多國家版本允許參照國家要修改的相關使用的有效哈密頓方法。
  • 對於小分子的多參考身份證明書(MRCI)方法可以產生非常精確波函數和能量。
  • 分子和激進分子,並描述了一個決定因素,也可以研究用耦合簇理論(閉殼殼和限制開放的CCSD(T))。

分子結構,振動頻率,熱力學

自動幾何優化使用技術分析或數值梯度可用。 這些程序可以被用來獲取平衡幾何構型,過渡態,等等都為地面和激發電子態。

振動頻率和熱力學計算量為超臨界/ CASSCF波函數採用二階導數分析。 數值的頻率也可提供。

該決議身份的方法(RI)和Cholesky分解(光盤版)可在HF/DFT/MP2/RASSCF/CASPT2水平逼近。解析梯度實施的“純粹”的DFT。 解析梯度遵循高頻,混合DFT和RASSCF近期療效。

激發態和電子光譜

MOLCAS特別是潛在的表面設計,研究為激發態。
  • 能源利用一切可能獲得的波函數的方法。 幾何優化也有可能為國家的平均RASSCF能量。
  • 過渡性質計算在RASSCF使用RASSCF國家一級交互方法,這是獨一無二的MOLCAS方案。
  • 相同的代碼也可以用來計算自旋軌道耦合的有效利用單電子哈密頓和所謂的SO原子平均場積分(AMFI)。
  • 自動搜索在RASSCF一級能源的障礙,錐形十字路口等對激發態的表面。
  • Vibrationally解決電子光譜可能獲得使用穆拉代碼計算平台過渡的偶極矩諧振動能級之間的兩個電子態。

環境影響

MOLCAS治療提供了新的可能性,在解決方案和高分子的分子系統。
  • 溶劑效應可以治療用翁薩格球形空腔模型或極化連續模型(PCM)的。
  • 結合量子力學和分子力學(MM)的計算就可以進行類似的蛋白質大分子的系統,分子團簇(水滴)等
  • 該程序創建的NEMO分子力場的MC / MD模擬已得到執行。 這些領域包括武力靜電,誘導,分散,交換排斥條款。 他們採用的計算方法對單個分子。










Molcas features

Wave Functions, Energies, Properties

MOLCAS uses the following wave function models in calculations of total energies, electronic structures and molecular properties:
  • Hartree-Fock combined with DFT. Direct or semi-direct schemes are used, which makes possible calculations at this level with more than a thousand basis functions.
  • Møller-Plesset second order perturbation theory (closed or restricted open shell) can be used for a cheap estimate of dynamic electron correlation effects.
  • Multiconfigurational SCF (CAS or RAS) is used to treat systems where the electronic structure is not well described by a single determinant. Allows state averaging for treatment of many electronic states. Wave function up to about a million electronic configurations can be studied.
  • Multiconfigurational second order perturbation theory (CASPT2) can be used to estimate dynamic electron correlation for electronic states obtained with the CASSCF method. A multi-state version allows the reference states to be modified by the correlation using an effective Hamiltonian approach.
  • For small molecules the multi-reference CI (MRCI) method can yield highly accurate wave functions and energies.
  • Molecules and radicals, well described by a single determinant, can also be studied using coupled-cluster theory (closed shell and restricted open shell CCSD(T)).

Molecular Structures, Vibrational Frequencies, Thermodynamics

Automatic geometry optimization using analytical or numerical gradient techniques are available. These procedure can be used to obtain equilibrium geometries, transition states, etc. both for ground and excited electronic states.

Vibrational frequencies and thermodynamical quantities are computed for SCF/CASSCF wave functions using analytical second derivatives. Numerical frequencies are also available.

The resolution of identity approach (RI) and Cholesky decomposition (CD) is available at the HF/DFT/MP2/RASSCF/CASPT2 level of approximation. Analytic gradients are implemented for "pure" DFT. Analytic gradients to follow for HF, hybrid DFT and RASSCF in the near furture.

Excited States and Electronic Spectra

MOLCAS is in particular designed to study potential surfaces for excited states.
  • Energies may be obtained using all the wave function methods. Geometry optimization is possible also for state average RASSCF energies.
  • Transition properties are computed at the RASSCF level using the RASSCF State Interaction Method, which is unique to the MOLCAS program.
  • The same code can also be used to compute spin-orbit coupling using a effective one-electron SO Hamiltonian and so called Atomic Mean Field Integrals (AMFI).
  • Automatic search at the RASSCF level for energy barriers, conical intersections, etc on excited state surfaces.
  • Vibrationally resolved electronic spectra may be obtained using the MULA code for computing transition dipole moments between harmonic vibrational levels of two electronic states.

Environmental Effects

MOLCAS gives new possibilities to treat molecules in solutions and macromolecular systems.
  • Solvent effects can be treated using the Onsager spherical cavity model or the Polarizable Continuum Model (PCM).
  • Combined QM and molecular Mechanics (MM) calculations can be performed on macromolecular systems like proteins, molecular clusters (droplets), etc.
  • The NEMO procedure for creating intermolecular force fields for MC/MD simulations has been implemented. These force fields include electrostatics, induction, dispersion, and exchange-repulsion terms. They are based on calculations on individual molecules.