Quantum Proton Effects from Density Matrix Renormalization Group Calculations.

We recently introduced [ 204103] the nuclear-electronic all-particle density matrix renormalization group (NEAP-DMRG) method to solve the molecular Schrödinger equation, based on a stochastically optimized orbital basis, without invoking the Born-Oppenheimer approximation. In this work, we combine the DMRG method with the nuclear-electronic Hartree-Fock (NEHF-DMRG) approach, treating nuclei and electrons on the same footing. Inter- and intraspecies correlations are described within the DMRG method without truncating the excitation degree of the full configuration interaction wave function.

Nuclear-electronic all-particle density matrix renormalization group.

We introduce the Nuclear-Electronic All-Particle Density Matrix Renormalization Group (NEAP-DMRG) method for solving the time-independent Schrödinger equation simultaneously for electrons and other quantum species. In contrast to the already existing multicomponent approaches, in this work, we construct from the outset a multi-reference trial wave function with stochastically optimized non-orthogonal Gaussian orbitals. By iterative refining of the Gaussians' positions and widths, we obtain a compact multi-reference expansion for the multicomponent wave function.

H as a five-body problem described with explicitly correlated Gaussian basis sets.

Various explicitly correlated Gaussian (ECG) basis sets are considered for the solution of the molecular Schrödinger equation with particular attention to the simplest polyatomic system, H . Shortcomings and advantages are discussed for plain ECGs, ECGs with the global vector representation, floating ECGs and their numerical projection, and ECGs with complex parameters. The discussion is accompanied with particle density plots to visualize the observations.

Explicitly correlated Gaussian functions with shifted-center and projection techniques in pre-Born-Oppenheimer calculations.

Numerical projection methods are elaborated for the calculation of eigenstates of the non-relativistic many-particle Coulomb Hamiltonian with selected rotational and parity quantum numbers employing shifted explicitly correlated Gaussian functions, which are, in general, not eigenfunctions of the total angular momentum and parity operators. The increased computational cost of numerically projecting the basis functions onto the irreducible representations of the three dimensional rotation-inversion group is the price to pay for the increased flexibility of the basis functions. This increased flexibility allowed us to achieve a substantial improvement for the variational upper bound to the Pauli-allowed ground-state energy of the molecular ion treated as an explicit five-particle system.

Generalized elimination of the global translation from explicitly correlated Gaussian functions.

This paper presents the multi-channel generalization of the center-of-mass kinetic energy elimination approach [B. Simmen et al., Mol.

New Approaches for ab initio Calculations of Molecules with Strong Electron Correlation.

Reliable quantum chemical methods for the description of molecules with dense-lying frontier orbitals are needed in the context of many chemical compounds and reactions. Here, we review developments that led to our new computational toolbox which implements the quantum chemical density matrix renormalization group in a second-generation algorithm. We present an overview of the different components of this toolbox.

Communication: Relation of centroid molecular dynamics and ring-polymer molecular dynamics to exact quantum dynamics.

We recently obtained a quantum-Boltzmann-conserving classical dynamics by making a single change to the derivation of the "Classical Wigner" approximation. Here, we show that the further approximation of this "Matsubara dynamics" gives rise to two popular heuristic methods for treating quantum Boltzmann time-correlation functions: centroid molecular dynamics (CMD) and ring-polymer molecular dynamics (RPMD). We show that CMD is a mean-field approximation to Matsubara dynamics, obtained by discarding (classical) fluctuations around the centroid, and that RPMD is the result of discarding a term in the Matsubara Liouvillian which shifts the frequencies of these fluctuations.

Boltzmann-conserving classical dynamics in quantum time-correlation functions: "Matsubara dynamics".

We show that a single change in the derivation of the linearized semiclassical-initial value representation (LSC-IVR or "classical Wigner approximation") results in a classical dynamics which conserves the quantum Boltzmann distribution. We rederive the (standard) LSC-IVR approach by writing the (exact) quantum time-correlation function in terms of the normal modes of a free ring-polymer (i.e.

Bellini duct (collecting duct) carcinoma of the kidney.

Carcinoma of the collecting ducts, or Bellini carcinoma, is a rare renal tumour and, unlike most renal cell carcinomas, it derives from distal tubules. It displays highly aggressive behaviour and has a poor prognosis. In this study, the authors present three cases which they observed over the past three years.

[Adrenalectomy and radical nephrectomy due to renal carcinoma].

Background: Surgery remains the only effective treatment for renal carcinoma. According the current surgical procedure, both the neoplastic kidney with its perirenal tissue and the Gerota fascia with adrenal gland must be removed. In the last years, the utility of routine adrenalectomy for kidney cancer surgery has been questioned and some authors now recommend this procedure just in selected cases.

Comparison between ultrasonography and computerized tomography in the identification of small-sized renal carcinomas.

Objectives: The increased detection of such small-sized carcinomas has brought a number of new problems regarding the surgical approach to be adopted. We review our experience with 34 patients with small-sized renal carcinomas, comparing the US and CT data with histological findings.

Methods: In a series of 150 cases of renal carcinoma, small sized carcinomas were diagnosed in 34 patients.

Renal adenocarcinoma with lung metastasis in an adolescent.

Objective: The finding of a renal adenocarcinoma in a young patient is a rare occurrence. We report on a case of renal adenocarcinoma with lung metastases arising in an 18-year-old girl with non-specific symptoms and normal blood chemistry and urinary analysis.

Results And Conclusion: We underscore the aggressive nature of the tumour which grew asymptomatically, giving rise to lymph node and pulmonary metastases.

[Multilocular cystic nephroma in children. Description of a case].

In paediatric age there may occur the various types of cystic renal tumor also of different clinical meaning; we can count among them shapes openly or potentially deadly, among which Wilms tumor cystic owing to haemorrhages and tumoral necrosis, congenital mesoblastic cystic nephroma, clear cell carcinoma, cystic, partially differentiated nephroblastoma (CPDN) and benign forms such as multilocular cystic nephroma (MLCN), cystic localized dysplasia of the kidney. In some cases, the differential diagnosis is difficult and it becomes only by histology: particularly the differential diagnosis between MLCN and CPDN, indistinguishable on the basis of the imaging and the macroscopic aspect, it is possible only by histology. It is described a case of multicystic lesion in a baby, male, aged twenty-two months, with an indolent mass of left side, screened by US and TC.

Small renal-cell carcinomas: clinical and imaging features.

The authors review the clinical, pathological and imaging characteristics of 20 patients with histological confirmation of 23 renal-cell carcinomas measuring < or = 3 cm in size. All lesions were unilateral. All patients were submitted to CT investigations, which identified 20 tumours (86%) and failed to identify 3 small-sized neoplastic nodular formations (0.

[Renal angiomyolipoma: diagnostic approach and therapeutic up-date; report of 11 clinical cases].

Eleven cases of renal angiomyolipoma are reported. In all cases a correct preoperative diagnosis was made, using standards x-radiography, ultrasonography and computerized tomography. Small size AML do not generally require any surgery, while surgical procedures for larger AML vary depending on the size, associated diseases, other complicating factors.

[Renal-colonic-cutaneous fistula secondary to xanthogranulomatous pyelonephritis].

The appearance of intestinal fistulas secondary to kidney disease is a rare occurrence. Even rarer are complex fistulas involving several organs or systems [correction of apparati]. In this study, the authors report on a case of reno-colo-cutaneous fistula which set in as a complication of xanthogranulomatous pyelonephritis.

[10 cases of xanthogranulomatous pyelonephritis].

Xanthogranulomatous pyelonephritis (XGP) is a chronic inflammation of the kidney usually associated with renal stones, recurrent urinary tract infections or endocrine disorders. A correct preoperative diagnosis is rarely made, since no specific clinical or radiological pattern is known. Differential diagnosis must include renal tuberculosis and renal carcinoma.

Thyroid metastases from renal carcinoma.

The identification and diagnosis of thyroid metastases from renal adenocarcinoma are rare in living patients, though more frequent during autopsy. A case is reported in which the identification of thyroid metastases indicated a clear-cell renal carcinoma in a kidney treated 12 years earlier for emptying of multiple cysts.

[Malignant neoplastic pathology in patients given a kidney transplant].

The incidence of malignant neoplasms in patients subjected to pharmacological immunosuppression following kidney transplantation is higher than that observed in the control population at large. In our unit, in a study population of 451 patients undergoing a total of 462 kidney transplants over the period from 1968 to 1986, four malignant neoplasms (0.9%) were observed in 3/369 (0.

[Hyperparathyroidism in patients having undergone a kidney transplant].

The persistence or onset of hyperparathyroidism following kidney transplant is characterized by an incidence ranging from 2.6 to 70% according to the various statistics available. In a total of 462 kidney transplants performed in our department, hyperparathyroidism was detected in 9 patients.

[Adenomatoid tumor of the epididymis].

Primary tumors of the epididymis are very rare. The neoplasms most frequently affecting the epididymis are adenomatoid tumors. In this report, the authors describe a case observed personally.